JP2004124766A - Valve system for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the eccentric wear by preventing an increase in the local surface pressure due to a fall of a tappet when driving a cam in a valve system, which is formed of a center tappet and side tappets on both sides and in which the side tappets and the center tappet abut on each other in a slide-contact surface in parallel with the axial direction of the cam in a direction crossing a cam shaft. <P>SOLUTION: Notch-like clearance parts 85a and 85b (85c and 85d) are formed in a valve side end of the side tappet 32 at a part facing to a slide-contact surface, which is provided in an end of the center tappet 31, to form the predetermined space between the end of the side tappet 31. With this structure, when the tappet 3 is tilted, an increase of the local surface pressure between the peripheral edge of the valve side end part of the side tappet 32 and the inner surface of a tappet guide hole 4 is restricted, and an increase in the local surface pressure between a lower end of the center tappet 31 and the inner surface of the tappet guide hole 4 is restricted to prevent the generation of eccentric wear. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a valve train for an engine, and more particularly, to a valve train for an engine in which a tappet that contacts a cam and slides in a tappet guide hole to drive a valve is composed of a center tappet and side tappets on both sides in a cam axial direction. Equipment related.
[0002]
[Prior art]
As a direct-type valve train that drives the intake and exhaust valves of engines for automobiles and the like directly by a cam via a tappet, the tappet is composed of a center tappet and side tappets on both sides in the cam axis direction. In the vicinity of the end on the valve side by a connecting portion extending substantially perpendicular to both side tappets, and a connecting portion with the valve stem is provided on a surface of the connecting portion on the side opposite to the cam, and between the side tappets on both sides. The center tappet is incorporated so as to be relatively movable, and the outer peripheral surface is formed into a substantially cylindrical shape, and can be connected and detached by a lock mechanism. 2. Description of the Related Art A valve operating device capable of changing an operating characteristic of a valve by a release operation has been conventionally known (for example, see Patent Documents 1 and 2). And, as the tappet, the side tappet has sliding contact surfaces extending in the tappet axis direction in parallel with the cam axis direction at both ends in the direction perpendicular to the camshaft, and the center tappet has side slides at both ends in the direction perpendicular to the camshaft. The tappet is formed in a substantially I-shape in plan view having a projection provided with a sliding contact surface that comes into contact with the sliding contact surface of the tappet, and the outer peripheral surface of the tappet formed by the center tappet and the side tappets on both sides is substantially cylindrical. Is known (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP 2001-329907 A
[Patent Document 2]
JP-A-2002-54413
[0004]
[Problems to be solved by the invention]
By the way, the tappet of the valve train is pushed by the cam and slides in the tappet guide hole. The tappet comes into contact with the cam at the top cam contact surface, and the cam contact surface is perpendicular to the cam shaft. Since the cam surface is pressed while sliding, a force is generated at the time of driving to tilt the tappet with respect to the tappet guide hole in a direction perpendicular to the cam shaft. If the tappet falls down significantly, local surface pressure between the tappet guide hole and the inner surface of the tappet increases, and uneven wear may occur.
[0005]
In particular, as described above, the tappet is composed of the center tappet and the side tappets on both sides in the cam axis direction, the center tappet is substantially I-shaped in plan view, and the side tappet and the center tappet are parallel to the cam axis direction. When the side tappet is pressed by the cam when the contact is made in the direction orthogonal to the cam shaft at the contact surface, the force is transmitted from the side tappet to the center tappet via the valve-side end of the sliding contact surface, and the center tappet skirt When the lower end of the portion is pushed or the center tappet is pushed by the cam, the center tappet tilts, so that the local surface pressure between the center tappet and the inner surface of the tappet guide hole increases, which may cause uneven wear.
[0006]
The present invention has been made in view of such a problem, and includes a center tappet and side tappets on both sides in the cam axis direction, and the side tappet and the center tappet have a sliding contact surface parallel to the cam axis direction. An object of the present invention is to provide a valve train using a tappet that abuts in a direction perpendicular to the valve to prevent an increase in local surface pressure due to a fall of the tappet at the time of driving a cam, thereby preventing uneven wear.
[0007]
[Means for Solving the Problems]
The valve train of the engine according to the present invention comprises a center tappet located at the center in the cam axis direction and side taps located on both sides in the cam axis direction, the tappet being in contact with the cam and sliding in the tappet guide hole to drive the valve. A tappet is formed at both ends in a direction perpendicular to the cam axis of the side tappet, and sliding contact surfaces extending in the tappet axis direction are formed in parallel with the cam axis direction, and the center tappet is formed at both ends in the direction perpendicular to the cam shaft. Formed in a substantially I-shape in plan view having projections protruding toward the side tappets on both sides and extending in the tappet axis direction, the inner side surface of each projection facing the direction orthogonal to the cam axis is defined as a cam shaft. It is a sliding surface that extends in the axial direction of the tappet in parallel and abuts against the sliding surface of the side tappet. The center tappet and the side tappet can be relatively moved in the tappet sliding direction, and the The cam is divided into a center cam corresponding to the center tappet and a pair of side cams corresponding to the side portions of the side tappet, and the cam profiles are different between the center cam and the pair of side cams. In the valve operating device of the engine, in which the operating characteristics of the valve can be changed by the coupling or disengagement operation of the lock mechanism, a portion of the side tappet on the valve side end facing the projection of the center tappet is provided with the center tappet. A notch-shaped relief portion is formed so as to form a predetermined space between the projection portion and the projection portion.
[0008]
In this manner, a notch-shaped relief portion is formed at a portion of the valve-side end of the side tappet facing the protrusion of the center tappet so as to form a predetermined space between the protrusion and the center tappet. Thus, when the tappet is tilted during driving, the side tappet can escape to the valve-side end, and the side tappet does not contact the center tappet at the valve-side end. In addition, the center tappet can be bent, and an increase in surface pressure between the lower end of the center tappet and the inner surface of the tappet guide hole can be prevented. Therefore, uneven wear due to the fall of the tappet during driving can be prevented.
[0009]
In this valve gear, the outer peripheral surface of the tappet composed of the center tappet and the side tappets on both sides is substantially cylindrical, and the side tappets on both sides are substantially perpendicular to both side tappets near the end on the valve side. The connecting portion has a connecting portion with the valve stem on the surface on the side opposite to the cam, and the lost motion spring seat portion protrudes from both sides of the connecting portion in a direction perpendicular to the cam shaft. Further, two lost motion springs for pressing the center tappet against the center cam when the lock mechanism is disengaged may be arranged between each lost motion spring seat portion and the back surface of the cam sliding portion of the center tappet. In particular, the lost motion spring seat portions may be formed so as to protrude in a direction orthogonal to the cam shaft beyond a surface connecting the sliding surfaces of both side tappets in the cam axis direction in plan view. . In this case, the slide contact surface requires high-precision cutting, and if the slide contact surface is provided up to the valve-side end of the side tappet, it must be processed avoiding the lost motion spring seat part. There is a possibility that the lost motion spring seat portion may be shaved, and it is difficult to machine the sliding contact surface. However, as described above, the side tappet is cut into a portion facing the projection of the center tappet on the valve side end. By forming a notch-shaped relief part, the sliding contact surface is just before the relief part, and it is not necessary to work by avoiding the lost motion spring seat part, processing of the sliding contact surface is easy, and lost motion during cutting The spring seat portion will not be scraped.
[0010]
If you have two lost motion springs and distribute them to both sides in the direction perpendicular to the camshaft, it is possible to arrange the springs avoiding the lock mechanism located in the center of the tappet, increasing the flexibility of the spring length This makes it possible to lengthen the spring and increase the stroke difference between the side tappet and the center tappet. The two lost motion springs are formed by projecting the lost motion spring seat portion in a direction perpendicular to the cam shaft beyond the surface connecting the sliding contact surfaces of both side tappets in the cam axis direction in plan view. It is easy to secure a space to be arranged between the center tappet and the rear surface of the cam sliding portion.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0012]
1 to 11 show a valve train of an engine according to an embodiment of the present invention. FIG. 1 is a front view showing a main part of the valve gear in a cross section orthogonal to the camshaft, FIG. 2 is a side view showing a main part of the valve gear in a cross section partially in parallel with the camshaft, and FIG. 3 is a tappet. , FIG. 4 is a vertical cross-sectional view in front view showing a center section orthogonal to the cam axis of the tappet, FIG. 5 is a bottom view of the tappet, and FIG. 6 is a vertical cross-sectional view in center view parallel to the cam axis of the tappet. FIG. 7 is a cross-sectional view in plan view passing through the center of the lock mechanism of the tappet, FIG. 8 is a vertical cross-sectional view in center view parallel to the cam shaft of the tappet side tappet alone, and FIG. 9 is a side tappet of tappet. FIG. 10 is a side view of a single side tappet, FIG. 11 is a bottom view of a single side tappet, FIG. 12 is a plan view of a single center tappet, and FIG. 13 is a front view of a single center tappet. .
[0013]
1 and 2, reference numeral 1 denotes a cam carrier disposed on an upper portion of a cylinder head of an engine, 2 denotes a cam shaft, 3 denotes a tappet, 4 denotes a tappet guide hole provided in a cam carrier, and 5 denotes a valve (an intake valve or Exhaust valve). As shown in FIGS. 3 to 7, the tappet 3 includes a center tappet 31 and a side tappet 32. In contrast to the tappet 3, the camshaft 2 has a high lift cam at a portion corresponding to the center tappet 31. A high-speed center cam 21 having a profile is provided, and low-speed side cams 22 and 23 having a low lift cam profile are provided at portions corresponding to the side tappets 32 on both sides of the center cam 21. Note that the side cams 22 and 23 sandwiching the center cam 21 may be stop cams having the same cam profile with a small lift amount that substantially stops the valve operation.
[0014]
The tappet 3 has a substantially cylindrical shape as a whole, and a center portion in the direction of a cam shaft (center axis of the camshaft 2) is constituted by a center tappet 31, and side portions are constituted by both side tappet bodies 32a and 32b of a side tappet 32. Is done. The upper surface of the center tappet 31 forms a substantially rectangular planar center cam contact surface that is long in the cam sliding direction (the direction orthogonal to the axis of the camshaft in plan view), and both side tappet bodies of the side tappet 32 are formed. The upper surfaces of 32a and 32b form a substantially crescent-shaped planar side cam contact surface which fills both sides of the center cam contact surface to form a circular cam contact surface as a whole.
[0015]
As shown in FIGS. 8 to 11, the side tappet 32 is configured such that a pair of side tappet bodies 32 a and 32 b constituting a side cam contact surface have ends opposite to the cam contact surface (hereinafter, referred to as “anti-cam side”). In the vicinity of the portion, it is integrally connected by a connecting portion 32c having a contact portion 33 with the valve stem end 51 (see FIG. 1) on the lower surface, and is formed in a substantially U shape in side view. At both ends in a direction perpendicular to the cam shaft, lost motion spring seat portions 34a, 34b are provided which project beyond sliding contact surfaces of sliding contact portions 42a, 42b, 42c, 42d described later in plan view. Lost motion springs 35a and 35b are installed on the motion spring seat portions 34a and 34b, and a space between the both side tappet bodies 32a and 32b as shown in FIGS. Tatapetto 31 is incorporated. In the tappet 3, the contact portion 33 on the lower surface of the connecting portion 32 c of the side tappet 32 contacts the stem end 51 of the valve 5 via the shim 6.
[0016]
As shown in FIGS. 12 and 13, the center tappet 31 extends vertically downward and vertically symmetrically from the edge of the substantially rectangular planar center cam contact surface on the side (both long sides) along the cam sliding direction. And a pair of outer peripheral surfaces 37a having an arc-shaped cross-section extending vertically downward and left-right symmetrically from the ends (both short sides) which are both ends in the direction orthogonal to the camshaft. , 37b, at both ends in the direction perpendicular to the camshaft, the outer side continuously projects from the outer peripheral surface in an arc shape toward the side tappet 32 (side tappet bodies 32a, 32b), and the inner side is the camshaft. Projections 38a, 38b, 38c projecting substantially perpendicularly from the front and rear end faces 36a, 36b in the cam axis direction so as to form a sliding contact surface extending in the tappet axis direction in parallel with the cam axis direction opposite to the direction orthogonal to. , 38d are in the axial direction of the tappet. It formed to project over the entire length, and is configured in a planar view substantially I-shaped as a whole. A through hole 39 is formed in the center of the upper portion of the center tappet 31 so as to penetrate between the front and rear end surfaces 36a and 36b in parallel with the cam axis direction.
[0017]
In addition, the side tappet 32 has a pair of inner end surfaces 40a, 40b that are substantially U-shaped in side view and extend inside the pair of left and right side tappet bodies 32a, 32b to face vertically downward as described above, The outer peripheral surfaces 41a and 41b each have an arc-shaped cross section and extend vertically downward and symmetrically from the edge of the side cam contact surface on the outer end side in the cam axis direction, and the cam sliding direction of the side tappet bodies 32a and 32b. At both ends (in a direction perpendicular to the camshaft), sliding contact surfaces extending in the tappet axis direction parallel to the camshaft direction so as to make sliding contact with the sliding contact surfaces of the projections 38a, 38b, 38c, 38d of the center tappet 31. The sliding contact portions 42a, 42b, 42c, 42d provided with are formed. The side tappet 32 has a through hole 39 in the center tappet 31 when the center cam contact surface of the center tappet 31 and the side cam contact surface of the side tappet 32 are flush with each other in the upper center of the side tappet bodies 32a and 32b. Through holes 43a, 43b penetrating from the inner end surfaces 40a, 40b to the outer peripheral surfaces 41a, 41b are provided in parallel with the cam shaft direction so as to communicate with each other without any step.
[0018]
In addition, the both side tappet bodies 32a, 32b of the side tappet 32 have the lost motion spring seat portions 34a, 34b at the valve-side end portions facing the protruding portions 38a, 38b, 38c, 38d of the center tappet 31. Notched relief portions 85a, 85b, 85c, 85d are formed so as to form a predetermined interval between the projections 38a, 38b, 38c, 38d of the center tappet 31 from the upper side (return-valve side) to the lower end. Is formed.
[0019]
In the center tappet 31 and the side tappet 32, the center cam sliding contact surface of the center tappet 31 contacts the base circle portion of the center cam 21, and the side cam sliding contact surface of the side tappet 32 contacts the base circle portion of the side cams 22, 23. In this state, the center cam sliding contact surface of the center tappet 31 and the side cam sliding contact surface of the side tappet 32 are substantially flush, and in this state, the through holes 39 of the center tappet 31 and the through holes 43a, 43b of the side tappet 32 are aligned. Communicate with
[0020]
A hydraulic plunger 71 is built in the through hole 43b of one side tappet body 32b of the side tappet 32 so as to be able to protrude into the through hole 56 of the center tappet 31 by hydraulic pressure, and a through hole 39 penetrating the center tappet 31 is provided. Has a built-in lock pin 72 that is pushed by the hydraulic plunger 71 and can protrude into the through hole 43a of the other side tappet body 32a of the side tappet 32. The lock pin 72 is connected to the center tappet 31 and the side. A return spring 73 that urges the tappet 32 to a position where the tappet 32 is separated from each other and relatively movable in the tappet sliding direction is built in.
[0021]
In the through hole 39 of the center tappet 31, the end face of the center tappet 31 is opened at a portion opening to front and rear end faces 36 a, 36 b facing the inner end faces 40 a, 40 b of both side tappet bodies 32 a, 32 b of the side tappet 32. Bushes 74 and 75 are inserted and fixed respectively so as to be flush with 36a and 36b. The bush 75 fixed to the end on the hydraulic plunger 71 side contacts the flange 76 on the outer periphery of the lock pin 72 to restrict the movement of the lock pin 72 toward the hydraulic plunger 71. The bush 74 fixed to the other end holds the return spring 73 in a compressed state between the bush 74 and the flange 76 on the outer periphery of the lock pin 72.
[0022]
Further, bushes 77 and 78 are inserted and fixed into both through holes 43a and 43b on the side tappet 32 side, respectively. Of these, the bush 78 inserted and fixed in the through hole 43b of the side tappet body 32b in which the hydraulic plunger 71 is built in, the outer peripheral side of the tappet is closed by an end wall 78a, and the inner side is a fitting for slidingly fitting the hydraulic plunger 71. A hole 78b is formed. The bush 77 inserted into and fixed to the through hole 43a of the other side tappet body 32a has a fitting hole 77b for fitting an end of the lock pin 72 on the inner side in the axial direction. It functions as a stopper that regulates The bushings 77 and 78 on the side tappet 32 side have end portions on the side of the center tappet 31 projecting from the through holes 61a and 61b by predetermined dimensions, respectively, and are inserted into and fixed to the through holes 56 of the center tappet 31 on the end faces thereof. They face each other at a predetermined interval.
[0023]
In the outer peripheral surface 41a of the side tappet body 32a on which the bush 77 is inserted and fixed (rear side), a portion where the through hole 43a is opened is notched vertically, and the cut portion is provided with the bush. A detent member 87 supported by a pin 86 supported by 77 so as to be swingable is mounted to prevent the tappet 3 from rotating in the circumferential direction.
[0024]
Further, the center tappet 31 has both side tappets of the side tappet 32 in the cam axis direction at portions of both end faces 54a, 54b facing the both side tappet bodies 32a, 32b of the side tappet 32 along a lower portion of the through hole 39. By protruding toward the inner end surfaces 40a, 40b of the bodies 32a, 32b, it is engaged with the ends of the inwardly protruding bushes 77, 78 mounted in the through holes 43a, 43b of the side tappet bodies 32a, 32b. Locking portions 89a and 89b to be stopped are provided. By locking the locking portions 89a and 89b on both sides with the bushes 77 and 78 on the side tappet 32 side, the center tappet 31 is restricted from moving upward in the tappet sliding direction.
[0025]
In this way, the through-holes 39, 43a, 43b, the hydraulic plunger 71, the lock pin 72, the return spring 73, and the like constitute a lock mechanism that allows the center tappet 31 and the side tappet 32 to be mutually connected and detached. I have.
[0026]
In this lock mechanism, when hydraulic pressure acts, the hydraulic plunger 71 moves to the lock pin 72 side and the end enters the through hole 39 on the center tappet 31 side, and the lock pin 72 opposes the return spring 73. The end of the lock pin 72 is moved into the through hole 43a of the other side (rear side) side tappet body 32a of the side tappet 32. At this time, the hydraulic plunger 71 straddles the divided part of the center tappet 31 and the one side (front side) side tappet body 32b of the side tappet 32, and the lock pin 72 moves the other of the center tappet 31 and the side tappet 32. The center tappet 31 and the side tappet 32 are straddled over the divided portion of the side tappet body 32a and cooperate with each other to be locked. When the hydraulic pressure is released, the return spring 73 pushes the lock pin 72 back to the hydraulic plunger 71 side, and the hydraulic plunger 71 returns to the original position, so that both end surfaces of the lock pin 72 are in the through holes 39 of the center tappet 31. Inside, the center tappet 31 and the divided portion of the side tappet 32 are substantially flush with each other, the center tappet 31 is separated from the side tappet 32, and the unlocked state (unlocked).
[0027]
As described above, the lock mechanism can be switched between the locked state and the unlocked state by the hydraulic pressure. In the locked state, the side tappet 32 and the center tappet 31 are connected, and the side tappet 32 and the center tappet driven by the center cam 21 are provided. 31 cooperates to lift the valve in a high speed manner. In the unlocked state, the center tappet 31 separates from the side tappet 32 and moves freely while being pressed by the center cam 21 by the lost motion springs 35a and 35b, so that the side tappet 32 drives the side tappets 22 and 23. Then, the valve is lifted in a low speed mode or substantially stopped.
[0028]
The side tappet 32 has bosses 81a, 81b formed around the through holes 43a, 43b inside the apexes (cam contact portions) of both side tappet bodies 32a, 32b. Continuing with the left and right boss portions 81a, 81b of the 32b, a continuous rib 82 extending downward in the axial direction and the tappet axial direction of the boss portions 81a, 81b, and connecting the left and right below the connecting portion 32c is formed. There is no skeleton around the bosses 81a and 81b and around the rib 82.
[0029]
Further, as described above, the tappet 3 has a cutout around the through hole 43a in the outer peripheral surface 41a of the side tappet body 32a on which the bush 77 for inserting the pin 86 is inserted and fixed (rear side). A detent member 87 is attached to the portion. This detent member 87 has a substantially rectangular plate shape, and one end of a pin 86 is inserted and fixed from a substantially vertical direction at a position eccentric to one side in the longitudinal direction.
[0030]
As shown in FIG. 2, the tappet guide hole 4 is engaged with a detent member 87 held on the tappet 3 side so that the tappet slide hole can be moved only in the tappet sliding direction. A groove 88 extending in the direction is provided. The locking member 87 is attached to the lock receiving pin 86 such that the upper end thereof is closer to the cam contact surface and is longer in the upward direction. Then, the rotation of the tappet 4 is regulated in cooperation with the groove 88 on the inner periphery of the tappet guide hole 4.
[0031]
The hydraulic pressure for operating the hydraulic plunger 71 of the lock mechanism is supplied from an oil pump (oil pressure source) and controlled by a hydraulic control valve (not shown). It is supplied to the working hydraulic chamber behind the plunger 71. Therefore, as shown in FIG. 1, an oil gallery 91 is provided in the cam carrier 1, and is branched from the oil gallery 91 so as to supply the hydraulic pressure from the oil gallery 91 to the lock mechanism of the tappet 3 so that the inside of the tappet guide hole 4 is formed. A hydraulic oil supply passage 93 is provided on the peripheral surface of the tappet guide hole 4 of the hydraulic oil supply passage 93 in a state where the side cam sliding contact surface of the side tappet 32 is in contact with the base circle portions of the side cams 22 and 23. An oil passage 94 to the working hydraulic chamber is formed in one side tappet body 32b of the side tappet 32 so as to communicate with the opening in the surface.
[0032]
The oil pressure from the oil pump (oil pressure source) is controlled by a hydraulic control valve and guided to an oil gallery 91, the side cam sliding contact surface of the side tappet 32 abuts the base circle portions of the side cams 22 and 23, and the hydraulic oil supply passage When the opening of the inner peripheral surface of the tappet guide hole 93 communicates with the oil passage 94 on the tappet side, it is introduced into the oil passage 94 on the tappet 3 side via the hydraulic oil supply passage 93 and the operating oil pressure on the back of the hydraulic plunger 71. Supplied to the room.
[0033]
As described above, the valve operating device of the engine according to this embodiment includes the projections 38a, 38b, 38c, and 38d of the center tappet 31 at the valve-side ends of the side tappets 32a and 32b of the side tappet 32. From the upper side (opposite the valve side) of the lost motion spring seat portions 34a, 34b to the lower end, a predetermined interval is formed between the protrusions 38a, 38b, 38c, 38d of the center tappet 31 so as to form a predetermined interval. By forming the cut-out relief portions 85a, 85b, 85c, 85d, when the tappet 32 is inclined at the time of driving, it can escape to the valve side end of the side tappet 32, and the outer edge of the valve side end of the side tappet 32 An increase in the surface pressure between the tappet guide hole 4 and the inner surface of the tappet guide hole 4 is prevented. Further, since the side tappet 32 does not come into contact with the center tappet 31 at the valve side end, the lower end of the center tappet 31 is not pushed by the side tappet 32 and the center tappet 31 bends, and the lower end of the center tappet 31 and the tappet guide. An increase in surface pressure with the inner surface of the hole 4 is prevented. Therefore, uneven wear due to the fall of the tappet 3 during driving can be prevented. In addition, since the relief portions 85a, 85b, 85c, and 85d are formed from above the lost motion spring seat portions 34a and 34b (reverse valve side) to the lower end of the side tappet 32, the sliding contact portions 42a, 42b, 42c, and 42d are formed. The lost motion spring seat portions 34a and 34b do not hinder the cutting of the sliding surface until just before the relief portion, so that the machining is easy and the lost motion spring seat portion is not scraped during the cutting.
[0034]
Further, as described above, the side tappet 32 extends downward continuously from the left and right boss portions 81a, 81b of the both side tappet bodies 32a, 32b, and the rib 82 is formed below and below the connecting portion 32c. Since the skeleton structure has no flesh around the bosses 81a and 81b and around the ribs 82, it is lightweight, has high rigidity, and has the continuous ribs 82 so that the molten metal can be made to flow smoothly during casting. Are better.
[0035]
In the above-described embodiment, the engine in which the cam carrier is mounted on the upper portion of the cylinder head with the cam carrier as a separate body has been described. However, the present invention is also applicable to an engine having an integrated cylinder head without the cam carrier as a separate body. Can of course be applied.
[0036]
【The invention's effect】
As is apparent from the above description, the valve train of the engine of the present invention is constituted by the center tappet and the side tappets on both sides in the cam axis direction, and the side tappet and the center tappet have sliding contact surfaces parallel to the cam axis direction. In a valve gear using a tappet abutting in a direction orthogonal to a camshaft, a portion of a valve-side end of a side tappet facing a projection of a center tappet is provided with a predetermined gap between the projection of the center tappet. By forming a notch-shaped relief portion to form an interval, an increase in surface pressure between the valve-side end outer edge of the side tappet and the inner surface of the tappet guide hole when the tappet is tilted is prevented, and the center tappet lower end is formed. It is possible to prevent an increase in surface pressure between the tappet guide hole and the inner surface of the tappet guide hole, thereby preventing uneven wear of the inner surface of the tappet guide hole.
[0037]
In addition, the two lost motion springs are distributed to both sides in the direction orthogonal to the camshaft.In particular, the lost motion spring seat part is moved beyond the surface connecting the sliding contact surfaces of both side tappets in the cam axis direction in plan view. In the case of a tappet projecting in a direction perpendicular to the axis, a relief portion is formed at the valve side end of the side tappet so that the sliding surface of the side tappet does not interfere with the lost motion spring seat portion in side view. Therefore, it is not necessary to avoid the lost motion spring seat portion for cutting the sliding surface of the side tappet, which facilitates the machining.
[Brief description of the drawings]
FIG. 1 is a front view showing a cross section orthogonal to a part of a camshaft of a main part of a valve train according to an embodiment of the present invention.
FIG. 2 is a side view showing a cross section parallel to a part of a camshaft of a main part of the valve train according to the embodiment of the present invention.
FIG. 3 is a plan view of a tappet of the valve train according to the embodiment of the present invention.
FIG. 4 is a vertical sectional view in front view showing a center section orthogonal to a cam shaft of a tappet of the valve train according to the embodiment of the present invention.
FIG. 5 is a bottom view of the tappet of the valve gear according to the embodiment of the present invention.
FIG. 6 is a side cross-sectional vertical view showing a center section parallel to a cam shaft of a tappet of the valve train according to the embodiment of the present invention.
FIG. 7 is a plan cross-sectional view passing through the center of the lock mechanism of the tappet of the valve train according to the embodiment of the present invention.
FIG. 8 is a vertical cross-sectional side view showing a center section parallel to a cam axis of a side tappet alone of the tappet of the valve train according to the embodiment of the present invention.
FIG. 9 is a plan view of a side tappet alone of the tappet of the valve gear according to the embodiment of the present invention.
FIG. 10 is a front view of a side tappet alone of the tappet of the valve gear according to the embodiment of the present invention.
FIG. 11 is a bottom view of a side tappet alone of the tappet of the valve gear according to the embodiment of the present invention.
FIG. 12 is a plan view of a center tappet alone of the tappet of the valve gear according to the embodiment of the present invention.
FIG. 13 is a front view of a center tappet alone of the tappet of the valve gear according to the embodiment of the present invention.
[Explanation of symbols]
2 camshaft
3 Tappet
4 Tappet Guide Hall
5 valves
21 Center cam
22, 23 Side cam
31 Center Tappet
32 side tappet
32a, 32b Side tappet body
32c connecting part
34a, 34b Spring seat part
35a, 35b Lost motion spring
36a, 36b end face
38a, 38b, 38c, 38d Projection
40a, 40b Inner end face
41a, 41b Outer peripheral surface
42a, 42b, 42c, 42d sliding contact portion
82 rib
85a, 85b, 85c, 85d Release part

Claims (3)

A tappet that contacts the cam and slides in the tappet guide hole to drive the valve is composed of a center tappet located at the center in the cam axis direction and side tappets located on both sides of the cam axis direction. At both ends in the direction perpendicular to the camshaft, sliding contact surfaces are formed extending in the tappet axis direction in parallel with the camshaft direction, and the center tappet is formed at both ends in the direction perpendicular to the camshaft toward the side tappets on both sides. It is formed in a substantially I-shape in plan view having a projection projecting and extending in the tappet axis direction, and the inner side surface of each projection facing the direction orthogonal to the cam axis is parallel to the cam axis in the tappet axis direction. The center tappet and the side tappet can be relatively moved in the tappet sliding direction by a sliding contact surface that extends and comes into contact with the sliding contact surface of the side tappet, and a locking mechanism is used. The cam is divided into a center cam corresponding to the center tappet and a pair of side cams corresponding to side portions of the side tappet, and a cam profile is formed by the center cam and the pair of side cams. In the valve operating device of the engine, the operating characteristics of the valve can be changed by coupling or releasing the lock mechanism.
A notch-shaped relief portion is formed at a portion of the valve-side end of the side tappet facing the protrusion of the center tappet so as to form a predetermined space between the protrusion and the center tappet. Characteristic engine valve gear. The outer peripheral surface of the tappet constituted by the center tappet and the side tappets on both sides is substantially cylindrical, and the side tappets on both sides are connected by a connecting portion extending substantially perpendicularly to both side tappets near the end on the valve side. The connecting portion has a connecting portion with the valve stem on the surface opposite to the cam side, and a lost motion spring seat portion is formed on both sides of the connecting portion in a direction orthogonal to the cam axis, and the lost motion spring seats are formed. 2. The two lost motion springs that press the center tappet against the center cam when the lock mechanism is disengaged are disposed between a spring seat portion and a rear surface of a cam sliding contact portion of the center tappet. 3. Engine valve gear. 3. The engine according to claim 2, wherein the lost motion spring seat portion is formed so as to protrude in a direction perpendicular to the cam shaft beyond a surface connecting the sliding contact surfaces of both side tappets in a cam axis direction in a plan view. 4. Valve train.

Images