JP3849602B2 - Engine valve gear - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a valve operating apparatus for an engine in which a valve is directly driven via a tappet, and belongs to the technical field of a vehicle engine.
[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 device 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. 30413 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 coupling and separating these tappets is provided. The lift amount of the valve is variable depending on whether the valve is lifted by a low speed cam or the valve is lifted by a high speed cam via a center tappet and both side tappets connected by a lock mechanism.
[0003]
[Problems to be solved by the invention]
By the way, if the two side tappets arranged opposite to each other are connected together at both ends of the connecting portion and are integrally called a tappet body, in this case, the tappet body is substantially U-shaped in a side view. It has become a shape. A center tappet is coupled to the tappet body, and in this state, is fitted to a cylindrical tappet guide provided in the cylinder head. Both side tappets are driven by low-speed cams that are in sliding contact with the respective top surfaces. On the other hand, the upper end of the stem end is in contact with the center of the back surface of the connecting portion.
[0004]
In this case, in the tappet main body, the center of the back surface of the connecting portion with which the stem end abuts is used as a fulcrum, and the pressure by the low speed cam acts on the top surface portions of both side tappets. Then, when the rigidity of the tappet body is low, there may be a problem that the connecting portion is curved. When the connecting portion is curved, both the side tappets appear to open upward, and the top surface portions of the both side tappets are pressed against the tappet guide, so that there is a possibility that friction between both the side tappets and the tappet guide increases. Further, when the friction between both side tappets and the tappet guide is increased as described above, energy loss is caused and engine efficiency is deteriorated. Furthermore, since wear of both becomes intense due to wear, durability is lowered.
[0005]
Therefore, an object of the present invention is to provide a valve gear for an engine including a tappet with increased rigidity.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention is configured as follows.
[0007]
First, the invention according to claim 1 of the present application is connected to the center tappet and located on both sides of the center tappet and below the center tappet. Makes a U-shaped tappet body in side view A pair of side tappets, and a connecting portion of the both side tappets The back center of Is provided with a contact portion of the valve stem, The upper surfaces of both side tappets are the top surfaces where the cams are in sliding contact, and in the substantially U-shaped side view, the upper side of both side tappets and the center tappet are extended in the left-right direction to slide the shaft member of the locking mechanism. A lock hole is provided so that the two side tappets and the center tappet are coupled and separated by the lock mechanism. A valve operating device for an engine using a split tappet, wherein the side tappet is , An outer peripheral wall portion fitted to the tappet guide of the cylinder head, an inner wall portion facing the side surface of the center tappet, and between the outer peripheral wall portion and the inner wall portion Built to form the lock hole With a hollow structure having a boss part, By connecting the boss portion of the side tappet, the outer peripheral wall portion, and the inner wall portion on both sides of the substantially U-shaped side view, and connecting the back surface of the connecting portion and the contact portion of the valve stem, respectively. , In plan view, extending in the axial direction of the bosses of the both side tappets, Between the boss part of one side tappet and the outer peripheral wall part and the inner wall part, the connecting part Reaching the contact portion of the valve stem through the back surface of And between the outer peripheral wall portion and the inner wall portion of the other side tappet to reach the boss portion of the side tappet. Columnar It is characterized in that continuous ribs are provided.
[0008]
According to the present invention, the side tappets on both sides are firmly connected by the rib, and the overall rigidity of the tappet body composed of both side tappets and the connecting portion, in particular, the tappet that has not been sufficiently rigid in the past. The rigidity of the main body in the cam shaft direction is increased. Accordingly, the connecting portion is less likely to be bent, and the problem of friction between the both side tappets and the tappet guide is solved, so that energy loss is eliminated and the durability of both is ensured.
[0009]
By the way, the tappet body may be processed by casting using a sand mold. In that case, according to the present invention, by providing a continuous rib in the hollow portion of the tappet body, the passage through which the molten metal flows is increased by that amount, and not only the flowability of the molten metal flowing through the entire cavity without gaps. In addition, when the molten metal flows in, the gas discharge performance of discharging all the gas filled in the cavity to the outside is improved.
[0010]
Next, the invention according to claim 2 is the valve operating device for an engine according to claim 1, wherein the outer peripheral wall portion of the side tappet is positioned on both sides of the boss portion and the rib, and the outer peripheral wall portion. An opening leading to the inside of the side tappet is provided at a position excluding the lower end of the side tappet.
[0011]
According to this invention, the side tappet can be reduced in weight by forming the opening. In that case, since the rigidity of the side tappet is lowered when the opening is formed up to the lower end of the outer peripheral wall, the opening is formed in a range that does not impair good rigidity. By carrying out like this, favorable rigidity maintenance and weight reduction in a side tappet can be made compatible.
[0012]
Further, by providing the opening, sand can be easily discharged from the hollow portion of the side tappet through the opening, and sanding workability after casting is improved.
[0013]
According to a third aspect of the present invention, in the engine valve operating apparatus according to the first or second aspect, the cam for one valve is composed of a high-speed cam and low-speed cams on both sides thereof. The four corners of the top surface portion of the center tappet with which the high-speed cam is slidably contacted are provided with protrusions that engage the outside of the outer peripheral wall portions of the side tappets on both sides, so that the top surface portion of the center tappet is substantially I-shaped. The center tappet and the side tappets on both sides form a substantially cylindrical surface that fits into the tappet guide.
[0014]
The top surface of the center tappet in a three-part type tappet is almost rectangular so that it fits between both side tappets, the long side is almost the same length as the inner wall of the side tappet, and the short side is a circle that fits the tappet guide. It is arcuate.
[0015]
Here, in the case of a valve lift by a high-speed cam, there is a problem that the pressing force of the center tappet against the tappet guide is large, and there is a concern about uneven wear between the two. On the other hand, in the case of a valve lift using a low-speed cam, there is also a problem that uneven wear occurs because the edge portion of the sliding surface of the side tappet with the center tappet is pressed against the tappet guide.
[0016]
Therefore, according to the present invention, the above-mentioned problem is solved by providing protrusions at the four corners of the top surface portion of the center tappet so that the top surface portion of the center tappet has a substantially I shape.
[0017]
First, in the case of a valve lift using a high-speed cam, the protrusion provided on the top surface of the center tappet engages the outside of the outer peripheral wall of the side tappet on both sides, so that the high-speed cam presses the center tappet against the tappet guide. Can be dispersed in the side tappet, and the problem of uneven wear is solved.
[0018]
In the case of a valve lift using a low-speed cam, the force that presses the side tappet against the tappet guide is distributed to the center tappet via the protruding portion, so the pressing force against the edge of the side tappet does not concentrate and wears unevenly. The problem is solved.
[0019]
According to a fourth aspect of the present invention, in the engine valve operating device according to any one of the first to third aspects, a pair of springs that press and urge the center tappet against the cam are provided on both sides of the lock mechanism. The receiving portion of both springs protrudes from the side and is integrally formed at the connecting portion.
[0020]
As in the present invention, the tappet provided with two springs for pressing and urging the cam side on both sides of the lock mechanism has a vertical movement of the center tappet incorporated in both side tappets, as compared with the case of one spring. It becomes smoother. In addition, by disposing the spring while avoiding the locking mechanism, it is possible to secure a long spring length, so that the amount of relative movement of the center tappet with respect to the side tappet can be increased, and as a result, a low speed cam is used. The difference in the lift amount of the valve between driving and driving with the high-speed cam can be further increased. For example, switching control between a high speed lift and a micro lift is possible.
[0021]
In addition, by adopting a structure in which a receiving seat for a pair of springs protrudes laterally on both sides of the connecting portion, the springs can be supported with a simple configuration.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0023]
First, the schematic configuration of the engine according to the present embodiment will be described with reference to FIGS. 1 and 2. The engine 1 includes four cylinders 5... 5 including a cylinder block 2, a cylinder head 3, and a cylinder head cover 4. The two intake ports 6 and 6 and the two exhaust ports 7 and 7 are provided for each cylinder 5, and two ports for opening and closing each of the ports 6, 6, 7, and 7 are provided. Intake valves 8 and 8 and two exhaust valves 9 and 9 are provided (in FIG. 1, only one of the two intake and exhaust ports and intake and exhaust valves is shown).
[0024]
Further, a valve mechanism support member 10 that extends over the entire length of the cylinder head 3 is disposed on the cylinder head 3 and fixed to the cylinder head 3 by bolts 11.
[0025]
The support member 10 is provided with a total of four tappet guides 12... 12 for each cylinder 5, and each tappet guide 12 has four tappets 13 for the intake valves 8 and 8 and the exhaust valves 9 and 9. 13 are each slidably fitted up and down.
[0026]
An intake camshaft 14 and an exhaust camshaft 15 are arranged in parallel on the upper surface of the support member 10, and a plurality of bearing portions 16 provided at both ends of the support member 10 and between the cylinders 5. ... 16 are rotatably supported.
[0027]
The camshafts 14 and 15 rotate in synchronization with a crankshaft (not shown), whereby the intake cams 17 and the exhaust cams 18 provided on the camshafts 14 and 15 are used for the intake valves 8 and 8 and the exhaust valves. The intake valves 8 and 8 and the exhaust valves 9 and 9 are opened and closed against the biasing force of the return springs 20 and 20 provided in the stem ends 19 and 19 through the 9 and 9 tappets 13. It has become.
[0028]
As shown in FIG. 1, the upper portion of the cylinder head 3 is covered with a head cover 4, and the valve mechanism support member 10 is positioned at the center of each cylinder 5 as shown in FIG. A spark plug mounting hole 21 is provided.
[0029]
Here, each of the cams 17 and 18 provided on the intake and exhaust camshafts 14 and 15 includes a high-speed cam 22 having a large lift amount provided at the center and a low-speed cam 23 having a small lift amount provided on both sides thereof. , 23 cams. Even if the cams having a substantially circular profile are used as the low-speed cams 23 and 23 and only a minute lift for preventing fuel from accumulating in the intake port is performed, a substantial valve stop state can be realized. Good.
[0030]
Next, the configuration of the tappet 13 which is a characteristic part of the present plan will be described in detail.
[0031]
As shown in FIG. 3, the tappet 13 accommodated in the tappet guide 12 includes a center tappet 30 having an I-shape in a plan view and a tappet body 31 that forms a cylindrical surface together with the center tappet 30. The center tappet 30 is configured such that a top surface portion 30a that contacts the high-speed cam 23 of the camshafts 14 and 15 has a long side in the sliding direction of the cam 22 indicated by an arrow a, while the tappet body 31 includes a low-speed cam. A pair of side tappets that are configured so that the top surface portions 32a and 33a that come into contact with 23 and 23 have long sides in the sliding direction of the cams 23 and 23 similarly indicated by an arrow a so as to sandwich the center tappet 30 therebetween. The tappet 13 is divided into three parts.
[0032]
As shown in FIG. 4, the center tappet 30 includes a top surface portion 30 a that provides a substantially rectangular flat surface that abuts on the high-speed cam 22 provided on the intake camshaft 14, and edges of the top surface portion 30 a along the cam sliding direction. Two arc-shaped outer peripheral walls that extend downward from both end portions in the cam sliding direction of the top surface portion 30a and form a cylindrical surface together with side tappets 32 and 33 described later. Parts 30c and 30c.
[0033]
Then, at the four corners where the outer peripheral wall portions 30c, 30c and the side surface portions 30b, 30b intersect, projecting portions 30d... 30d projecting along the cylindrical surface are formed.
[0034]
Further, a boss portion 30e extending in the cam shaft direction is formed on the back side of the top surface portion 30a of the center tappet 30, and a lock hole 30f penetrating both side surface portions 30b and 30b is formed in the boss portion 30e. Yes. A pair of spring seats 30g and 30g are formed on both sides of the boss 30e on the back side of the top surface 30a.
[0035]
As shown in FIG. 5, the pair of side tappets 32 and 33 are connected at the lower portion by a connecting portion 34 to constitute a substantially U-shaped tappet body 31 in a side view. On the side tappets 32 and 33, two top surface portions 32a and 33a that provide a flat surface that abuts on the low-speed cams 23 and 23 provided on the intake camshaft 14 have sliding directions of the cams 23 and 23 indicated by arrows a. It is formed along. Further, the side tappets 32 and 33 have two inner wall portions 32b and 33b extending downward from edges along the cam sliding direction of the top surface portions 32a and 33a, and the top surface portions 32a and 33a in the direction of the intake camshaft 14. Two substantially arc-shaped outer peripheral wall portions 32c and 33c extending downward from both end portions are formed.
[0036]
Protruding portions (only one of them is shown in FIG. 5) 34a and 34a are extended at both ends of the connecting portion 34 along the cam sliding direction, and springs receiving seats are respectively provided on the protruding portions 34a and 34a. 34b and 34b are formed.
[0037]
Further, the side tappets 32 and 33 are formed with protrusions 32d, 32d, 33d and 33d extending in the direction of the center tappet 30 from both ends of the inner wall portions 32b and 33b in the cam sliding direction in a non-contact state with the center tappet 30. Has been.
[0038]
Further, the side tappets 32, 33 extend downward from both end portions of the top surface portions 32a, 33a in the cam sliding direction, and the lateral wall portions 32e, 32e, 33e, 33e are in sliding contact with the protruding portions 30d ... 30d of the center tappet 30. Is formed.
[0039]
Boss portions 32f and 33f extending in the camshaft direction are formed on the back side of the top surface portions 32a and 33a of the side tappets 32 and 33, and penetrate from one outer peripheral wall portion 32c to the other outer peripheral wall portion 33c. Thus, lock holes 32g and 33g that pass through the axis of the tappet 13 and are parallel to the direction of the intake camshaft 14 are formed. The lock holes 32g and 33g communicate with the lock hole 30f of the center tappet 30 in a straight line when the top surface portion 30a of the center tappet 30 and the top surface portions 32a and 33a of the side tappets 32 and 33 are flush with each other. It is formed as follows.
[0040]
By doing so, the center tappet 30 is assembled between the tappet main body 31, that is, the side tappets 32, 33, and the outer peripheral wall portions 30 c, 30 c, 32 c, 33 c of these tappets 30, 32, 33 and the tappet guide 12 are slid. The protrusions 30d to 30d of the center tappet 30 and the lateral wall portions 32e, 32e, 33e, and 33e of the side tappets 32 and 33 can slide. The center tappet 30 is incorporated in the tappet body 31 with a spring interposed therebetween, and can be moved relative to the side tappets 32 and 33 against the urging force of the spring.
[0041]
A lock mechanism for coupling and separating the center tappet 30 incorporated so as to be movable relative to the side tappets 32 and 33 and the side tappets 32 and 33 connected to the stem end 19 of the intake valve 8 will be described with reference to FIGS. Based on
[0042]
First, a pair of springs 35, 35 that press and urge the center tappet 30 against the high-speed cam 22 are disposed between the receiving seats 30 g, 30 g of the center tappet 30 and the receiving seats 34 b, 34 b of the side tappets 32, 33. ing.
[0043]
Further, as described above, the lock hole 30f of the center tappet 30 and the lock holes 32g and 33g of the side tappets 32 and 33 are formed by the top surface portion 30a of the center tappet 30 and the top surface portions 32a and 33a of the side tappets 32 and 33. When in a flush state, they communicate in a straight line in the direction of the intake camshaft 14.
[0044]
A plunger 40 that advances into the lock hole 30f of the center tappet 30 by hydraulic pressure is inserted into the lock hole 33g of one side tappet 33, and the other side tappet 32 is pressed into the lock hole 30f of the center tappet 30 by the plunger 40. A lock pin 41 that advances into the lock hole 32g of the lock pin 41 is provided around the lock pin 41 via a flange portion 41a that is provided near the plunger 40 of the lock pin 41. The springs 42 for biasing are arranged respectively.
[0045]
Further, bushes 43 and 44 are inserted and fixed in the vicinity of both ends of the lock pin 41 in the lock hole 30f of the center tappet 30, respectively. Of the bushes 43 and 44, the bush 43 closer to the plunger 40 abuts on the flange portion 41 a of the lock pin 41 and restricts the movement of the lock pin 41 beyond the outer surface 30 b of the center tappet 30 toward the plunger 40. . The other bush 44 compresses and holds the spring 42 between the flange portion 41a.
[0046]
Further, separate bushes 45 and 46 are inserted and fixed in the lock holes 32g and 33g of the both side tappets 32 and 33, respectively. The bush 45 on the plunger 40 side of the bushes 45 and 46 is configured to open facing the lock pin 41, and the plunger 40 is slidably fitted inward. The other bush 46 accommodates the tip end portion of the lock pin 41 that enters, and has a stopper portion 46 a that restricts the lock pin 41 from entering a predetermined length or more.
[0047]
The end portions 45a and 46b of the bushes 45 and 46 on the center tappet 30 side have predetermined lengths in the gaps between the side surface portions 30b and 30b of the center tappet 30 and the inner wall portions 32b and 33b of the side tappets 32 and 33, respectively. It is arranged so as to protrude.
[0048]
Thus, a lock mechanism is configured by the lock holes 30f, 32g, 33g, the plunger 40, the lock pin 41, the spring 42, and the like.
[0049]
Further, a ball member 47 is supported so as to partially protrude from a ball support portion 46 c provided on the outer peripheral side of the tappet 13 of the bush 46, while on the sliding surface of the tappet guide 12 with the tappet 13, A guide groove 12 a is formed to be able to engage with the ball member 47 along the sliding direction of the tappet 13.
[0050]
By doing so, the rotation around the axis of the tappet 13 in the tappet guide 12 is regulated through the engagement between the ball member 47 and the guide groove 12a. As a result, a favorable sliding position relationship between the tappet 13, that is, the center tappet 30 and the side tappets 32, 33 and the cams 22, 23, 23 is maintained.
[0051]
Further, as shown in FIG. 1, lubricating oil is applied to the tappet guide 12 and the tappet 13 at portions around the opening of the tappet guide 12 around the cams 22, 23, and 23. Oil receiving recesses 12b and 12b are provided to be supplied to the sliding surfaces of the center tappet 30 and the side tappets 32 and 33. These oil receiving recesses 12b and 12b are provided so as to be inclined downward on the tappet 13 side.
[0052]
As shown in FIGS. 1 and 2, the support member 10 includes an inflow oil passage 50 for introducing working oil pressure from an oil pump (not shown), that is, a hydraulic power source, and a hydraulic control valve 51 for controlling the working oil pressure. In addition, an oil outflow passage 54 for supplying oil from the hydraulic control valve 51 to the oil gallery 52 and 53 extending along the intake and exhaust camshafts 14 and 15 is provided. Further, a branch oil passage 52a branched from the oil gallery 52, 53 and opened to the inner peripheral surface of each tappet guide 12 ... 12 so as to supply the oil pressure from the oil gallery 52, 53 to the lock mechanism of each tappet 13 ... 13. ... 52a, 53a ... 53a are provided.
[0053]
As an example, the opening on the inner peripheral surface of the tappet guide 12 of the branch oil passage 52a is such that the top surface portions 32a and 33a of the side tappets 32 and 33 are in contact with the base circle portions of the low-speed cams 23 and 23, as shown in FIG. As shown in FIG. 4, the oil passage 55 communicates with one side tappet 33. The side tappet 33 includes an oil passage 56 that communicates with the oil passage 55 and an oil passage 57 that communicates the oil passage 56 and the space 45 c behind the plunger 40 via an opening 45 b formed in the bush 45. Is provided.
[0054]
By doing so, the hydraulic pressure for operating the plunger 40 in the lock mechanism is controlled by the hydraulic control valve 51, and is supplied to the space 45c via the branch oil passage 52a during the high speed operation of the engine 1 that locks the lock mechanism. Is done. That is, the operating hydraulic pressure is introduced into the hydraulic control valve 51 through the inflow oil passage 50. When the hydraulic control valve 51 is turned on, the hydraulic pressure is guided from the hydraulic control valve 51 through the outflow oil passage 54 to the oil gallery 52 and branched. The oil passage 52a is introduced into the oil passage 55 through the branch oil passage 52a in a state where the opening portion of the inner peripheral surface of the tappet guide 12 of the oil passage 52a communicates with the oil passage 55 of the side tappet 33. It is supplied to the space 45 c behind the plunger 40 through the opening 45 b of the bush 45 via the path 57. On the other hand, when the hydraulic control valve 51 is turned off, the hydraulic pressure is released from the space 45c.
[0055]
Here, the structure of the tappet body 31, which is a feature of the present invention, will be described with reference to FIGS. The tappet body 31 is configured by arranging two side tappets 32 and 33 arranged to face each other and connecting them by a connecting portion 34. The side tappets 32 and 23 have a hollow structure surrounded by top surface portions 32a and 32a, inner wall portions 32b and 32b, outer peripheral wall portions, 32c and 32c, and lateral wall portions 32e, 32e, 33e, and 33e.
[0056]
Further, inside the both side tappets 32 and 33 and the connecting portion 34, the connecting portion 34 and the other side tappet 33 are arranged between the boss portion 32 f of one side tappet 32 and the outer peripheral wall portion 32 c and the inner wall portion 32 b. A continuous rib 36 is provided so as to reach the boss portion 33f of the side tappet 33 through a space between the outer peripheral wall portion 33c and the inner wall portion 33b and to be positioned on a plane perpendicular to the cam sliding direction. At this time, the rib 36 divides the hollow structure of the side tappets 32 and 33 into two. In this embodiment, the boss portions 32f and 33f are directly coupled to the back surfaces of the top surface portions 32a and 33a. However, when the boss portions 32f and 33f and the top surface portions 32a and 33a are separated from each other, What is necessary is just to set it as the structure which extends the said rib 36 between the back surfaces of 33f and the top surface parts 32a and 33a.
[0057]
On the other hand, the inner wall portions 32b and 33b and the outer peripheral wall portions 32c and 33c of both side tappets 32 and 33 are provided with openings 32h leading to the inside of the side tappets 32 and 33 at positions on both sides of the boss portions 32f and 33f and the rib 36. ... 32h, 33h ... 33h are provided. Two openings 32h... 32h, 33h... 33h are formed on both sides of the boss portions 32f and 33f in the inner wall portions 32b and 33b and the outer peripheral wall portions 32c and 33c of the side tappets 32 and 33, respectively. The vertical width of each of the openings 32h... 32h, 33h... 33h is formed extending downward from the bosses 32f and 33f, but the lower part is not opened up to the lower ends of the side tappets 32 and 33. Further, the lateral widths of the openings 32h... 32h, 33h... 33h formed in the inner walls 32b and 33b extend from the vicinity of the ribs 36 to the vicinity of the protrusions 32d, 32d, 33d and 33d, and these openings 32h. 33h... 33h has a substantially square shape.
[0058]
On the other hand, projecting portions 34a and 34a are integrally formed on both sides of the connecting portion 34 that connects the side tappets 32 and 33 so as to project sideways. In the center of the protrusions 34a and 34a, circular receiving seats 34b and 34b are provided so that the lower ends of a pair of springs 35 and 35 that press and urge the center tappet 30 against the cam 22 are fitted. A valve stem abutting portion 34 c that abuts on the stem end 19 is provided at the center of the back surface of the connecting portion 34.
[0059]
By providing the ribs 36 on the tappet main body 31 in this way, the side tappets 32 and 33 on both sides are firmly connected, and the tappet main body 31 composed of the side tappets 32 and 33 and the connecting portion as a whole. The rigidity of the tappet body 31 in the cam shaft direction, which has been insufficient in rigidity, in particular, is increased. Accordingly, the connecting portion 34 is less likely to be bent, and the problem of friction between the both side tappets 32 and 33 and the tappet guide 12 is solved. Therefore, energy loss is eliminated, and durability of both is ensured.
[0060]
The tappet body 31 is processed by casting using a sand mold 60. As shown in FIG. 10, at the time of casting, molten metal (this is called hot water) is poured into a cavity 62 reflecting the tappet body 31. At this time, the ribs 36 are provided to divide the cavity 62 and increase the number of passages of the molten metal, so that the oil flowability is improved, and the molten metal can reach the entire cavity 62 without any gaps, and the gas discharge performance is improved. Thus, when the molten metal flows in, the gas filled in the cavity is discharged well.
[0061]
Therefore, even if it has a complicated hollow structure like the tappet main body 31, casting defects can be reduced, and a sound tappet main body 31 can be obtained.
[0062]
On the other hand, the outer peripheral wall portions 32b and 33b of both side tappets 32 and 33 communicate with the inside at both sides of the boss portions 32f and 33f of both side tappets 32 and 33 and both sides of the rib 36 of the outer peripheral wall portions 32b and 33b. Opening portions 32h... 32h, 33h... 33h are formed to reduce the weight of the tappet body 31. If the openings 32h... 32h, 33h... 33h are cut open to the lower ends of the side tappets 32 and 33, the rigidity of the tappet body 31 in the cam sliding direction is impaired.
[0063]
Further, by providing openings 32h... 32h, 33h... 33h in the side tappets 32 and 33, after casting using the sand mold 60, sand is discharged from the hollow portions through the openings 32h... 32h, 33h. It can be easily discharged, and the sanding workability performed after metal solidification is improved.
[0064]
On the other hand, protrusions 30d... 30d are provided at the four corners of the top surface portions 30a, 30a of the center tappet 30 so that the top surface portions 30a, 30a of the center tappet 30 are substantially I-shaped. Thus, in the case of the valve lift by the high-speed cam 22, the high-speed cam 22 causes the center tappet 30 to be moved by the protrusions 30 d... 30 d engaging with the outside of the outer peripheral wall portions 32 c and 33 c of the side tappets 32 and 33 on both sides. The pressing force against the tappet guide 12 can be distributed to the side tappets 32 and 33, and the problem of uneven wear is solved.
[0065]
Further, in the case of the valve lift by the low speed cams 23, 23, the force for pressing the side tappets 32, 33 against the tappet guide 12 is distributed to the center tappet 30 through the projecting portions 30d ... 30d. The force of pressing on the part is not concentrated, and the problem of uneven wear is solved.
[0066]
The tappet 13 provided with a pair of springs 35 and 35 that press and urge the cam mechanism on both sides of the lock mechanism has a center tappet 30 incorporated in both side tappets 32 and 33, as compared with a case where there is one spring. The up-and-down movement is smoother. In addition, since the springs 35 and 35 are disposed so as to avoid the locking mechanism, the length of the springs 35 and 35 can be ensured long, so that the amount of relative movement of the center tappet 30 with respect to the side tappets 32 and 33 is further increased. Thus, the difference in lift amount of the valves 8, 8, 9, 9 during driving by the low speed cam and driving by the high speed cam can be further increased. For example, switching control between a high speed lift and a micro lift is possible.
[0067]
In addition, the springs 35 and 35 can be supported with a simple configuration by forming the receiving seats 34b and 34b of the pair of springs 35 and 35 on both sides of the connecting portion 34 so as to protrude sideways. It becomes possible.
[0068]
In the above embodiment, the openings 32h... 32h, 33h... 33h are formed on the outer peripheral wall portions 32c and 33c and the inner wall portions 32b and 33b, but the openings on the inner wall portions 32b and 32b are provided for design reasons. 32h ... 32h, 33h ... 33h can be omitted.
[0069]
【The invention's effect】
As described above, according to the present invention, in the tappet mounted on the valve gear of the engine, the boss portion of one side tappet is connected between the outer peripheral wall portion and the inner wall portion, the connecting portion, and the other side tappet. By providing a continuous rib between the outer peripheral wall part and the inner wall part to reach the boss part of the side tappet, the rigidity in the cam shaft direction of both side tappets increases, and the tappet body when driven by the cam Opening can be avoided. As a result, since the problem of friction between the side tappet and the tappet guide is solved, energy loss is eliminated and the durability of both can be ensured. Moreover, since the opening part which connects the outer periphery and the inside of the side tappet is formed on both sides of the ribs of the inner wall part and the outer peripheral wall part, it is possible to achieve both good rigidity maintenance and weight reduction of the side tappet. Is widely suitable in the field of vehicles equipped with engine valve gears.
[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 tappet body.
FIG. 6 is a longitudinal sectional view of an essential part centering on a tappet.
7 is a cross-sectional view taken along the line II in FIG.
FIG. 8 is a bottom view of the tappet body.
FIG. 9 is a side view of the tappet body.
FIG. 10 is a view for explaining a hot water flow property during casting.
[Explanation of symbols]
1 engine
2 Cylinder head
12 Tappet guide
13 Tappet
17,18 cam
22 High speed cam
23 Low speed cam
30 Center tappet
30a Top surface
30d protrusion
32, 33 Side tappet
32a, 33a Top surface
32b, 33b Inner wall
32c, 33c Outer peripheral wall
32f, 33f Boss
32h, 33h opening
34 Connecting part
34a protrusion
34b seat
34c Valve stem contact part
35 Spring
36 ribs

Claims (4)

A center tappet, are connected in and below the center tappet located on both sides and a pair of side tappet forming a substantially U-shaped tappet body in side view, the center of the back surface of the connecting portion of the both side tappets A valve stem contact portion is provided, and the upper surfaces of both side tappets are the top surface portions where the cams are slidably in contact with each other, and the upper side of the side tappets on both sides and the center tappet in the substantially U-shaped side view. A valve operating device for an engine using a split type tappet that extends in the left-right direction and is provided with a lock hole that slidably accommodates a shaft member of the lock mechanism, and the side tappet and the center tappet are coupled and separated by the lock mechanism. there are, the side tappet includes a peripheral wall portion which is fitted into the tappet guide of the cylinder head, among which faces the side surface of the center tappet And parts, are installed between the outer peripheral wall and the inner wall portion with being a hollow structure having a boss portion forming the locking hole, the both sides of the substantially U-shaped side view, respectively, By connecting the boss portion of the side tappet, the outer peripheral wall portion, and the inner wall portion, and connecting the back surface of the connection portion and the contact portion of the valve stem, the shafts of the boss portions of the both side tappets in a plan view. extending in a direction, between the outer peripheral wall portion and the inner wall portion from the boss portion of one of the side tappet, through the rear surface of the connecting portion reaches the contact portion of the valve stem further back side of the connecting portion and the other side, A valve operating apparatus for an engine, characterized in that a row of continuous ribs extending between an outer peripheral wall portion and an inner wall portion of the tappet and reaching a boss portion of the side tappet is provided. The outer peripheral wall portion of the side tappet is provided with an opening that leads to the inside of the side tappet at a position on both sides of the boss portion and the rib and excluding the lower end portion of the outer peripheral wall portion. The valve gear for an engine according to claim 1. The cam for one valve is composed of a high-speed cam and low-speed cams on both sides of the cam, and the four corners of the top surface of the center tappet with which the high-speed cam slides are engaged with the outside of the outer peripheral wall of both side tappets. The center tappet has a substantially I-shaped top surface, and the center tappet and side tappets on both sides constitute a substantially cylindrical surface that fits into the tappet guide. The valve operating apparatus for an engine according to claim 1 or 2. A pair of springs for pressing and urging the center tappet against the cam are disposed on both sides of the lock mechanism, and a receiving seat for both springs protrudes laterally at the connecting portion. The engine valve operating device according to any one of claims 1 to 3.

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