JP2020023916A - Tappet structure - Google Patents

Abstract

To provide a tappet structure which has excellent assemblability.SOLUTION: A tappet structure includes: a lash adjuster 20 having a convex curve surface-like apex 24 protruding upward; a tappet case 40 in which the lash adjuster 20 is assembled; a rocker arm 80 having a convex curve surface-like rod contact part 88 protruding downward; and a push rod 10 extending from an upper end part of the rocker arm 80 side to a lower end part of the lash adjuster 20 side. The push rod 10 has concave curve surface-like slide parts 11, 12 coming into contact with both of the rod contact part 88 and the apex part 24 and capable of sliding, at the upper end part and the lower end part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a tappet structure.

  The tappet structure disclosed in Patent Literature 1 includes a push rod extending from an upper end to a lower end, and a tappet with which the lower end of the push rod contacts. The upper end of the push rod is in contact with one end of the arm. The lowermost surface of the tappet is in contact with the cam. When the cam rotates, one end of the arm is pushed up via the tappet and the push rod. The arm is swung about the rocker shaft and pushes down the valve stem at the other end to open the valve.

  Further, the tappet structure disclosed in Patent Document 2 does not directly support the push rod by the tappet, but a lash adjuster is incorporated in the tappet, and the top of the lash adjuster abuts on the lower end of the push rod, The tappet has a structure in which the push rod is indirectly supported via a lash adjuster. According to this, the rocking fulcrum position of the rocker arm is appropriately adjusted by the lash adjuster, and the valve clearance can be eliminated.

JP 2013-96338 A International Publication No. WO 2015/067252

  The push rod provided in the tappet structure as described above has a situation in which the upper end and the lower end have different shapes, and cannot be assembled if an operator makes an incorrect vertical orientation. For this reason, it is necessary for the operator to confirm the vertical direction of the push rod at the time of assembly, which hinders quick work.

  The present invention has been completed based on the above circumstances, and has an object to provide a tappet structure excellent in assembling property.

  The tappet structure of the present invention includes a lash adjuster, a tappet case, a rocker arm, and a push rod. The lash adjuster has a convex curved top that protrudes upward. The tappet case has a lash adjuster assembled from above and reciprocates in accordance with the rotation of the cam. The rocker arm extends from one end to the other end in a direction intersecting the vertical direction, has a valve contact portion at one end where the valve contacts, and a convex curved rod contact portion protruding downward at the other end. Having. The push rod extends from the upper end on the rocker arm side to the lower end on the lash adjuster side, and has a concave curved sliding portion that can slide on the upper end and the lower end by contacting both the rod contact portion and the top portion. Having.

  Since the sliding portions at the upper end and the lower end of the push rod have a concave curved surface and are slidable in contact with both the rod contact portion and the top portion, the vertical direction (posture) of the push rod is reversed. You can still use it. Therefore, good assemblability can be ensured.

1 is an overall view of a valve train having a tappet structure according to a first embodiment of the present invention. It is an enlarged view of the lower part of FIG. It is an enlarged view of the upper part of FIG. It is a front view of a push rod.

Preferred embodiments of the present invention are described below.
(1) The sliding portions at the upper end and the lower end of the push rod have the same shape. According to this, the operator does not become confused about the necessity of distinguishing the vertical direction of the push rod, and the work (assembly work) can be performed more quickly.

  (2) The rocker arm extends from the one end to the other end, is attached to the arm main body having the valve contact part by screwing to the other end of the arm main body, and is provided below the arm main body. And an adjusting screw having a rod contact portion at a lower end portion. According to this, since the lower end of the adjusting screw may be provided with a convexly curved rod abutting portion projecting downward, machining of the rocker arm can be facilitated.

<Example 1>
Hereinafter, a first embodiment will be described with reference to FIGS. The tappet structure according to the first embodiment exemplifies a valve lifter of an OHV type engine. As shown in FIG. Have. In the following description, the vertical direction is not limited to the strict vertical direction (gravity direction) and includes a direction inclined with respect to the vertical direction, based on the state of use shown in FIG.

  As shown in FIG. 3, the rocker arm 80 includes an arm body 81 extending from one end to the other end in a direction intersecting the vertical direction, an adjusting screw 82 attached to the other end of the arm body 81, and an adjusting screw 82. And a nut 83 to be screwed.

  The arm body 81 has a shaft hole 84 at an intermediate portion in a length direction (a direction intersecting the vertical direction). The rocker arm 80 is swingably supported by a rocker shaft 90 inserted through the shaft hole 84. The rocker shaft 90 extends in the thickness direction of FIG. 3 and has a shaft oil hole 91 in which hydraulic oil flows.

  One end of the arm body 81 is a valve contact portion 87 that slidably contacts the upper end of the valve stem 93. The valve stem 93 is inserted into a valve guide hole 95 of the cylinder head 94. The lower end of the valve stem 93 is connected to a valve body 96 having an enlarged diameter. The valve body 96 is arranged so as to face an intake or exhaust port 97 of the cylinder head 94. The valve body 96 receives the urging force of the valve spring 98 to close the intake or exhaust port 97, and the valve stem 93 is pushed down by the valve contact portion 87 against the urging force of the valve spring 98. The state can be displaced.

  The adjusting screw 82 has a male screw part 99 on the outer peripheral surface, and is mounted in a mounting hole 85 provided in the other end of the arm main body 81 with the axis thereof oriented vertically (axially). The upper end of the adjusting screw 82 projects upward from the upper surface of the arm body 81, and the lower end of the adjusting screw 82 projects downward from the lower surface of the arm body 81. The adjusting screw 82 is screwed with a nut 83 at the upper end. The male screw 99 of the adjust screw 82 is screwed into the mounting hole 85 of the arm body 81, and after the amount of screw is determined, the nut 83 is tightened and fixed to the upper end of the adjust screw 82.

  The adjusting screw 82 communicates with the shaft oil hole 91 via a communication hole 89 provided in the arm body 81 and has a screw oil hole 79 extending in the vertical direction. The adjusting screw 82 has, at a lower end portion thereof, a rod contact portion 88 having a convex curved surface projecting downward, specifically, a hemispherical convex surface. The lower end of the screw oil hole 79 is opened at the center of the rod contact portion 88 in the radial direction.

  As shown in FIG. 2, a lash adjuster 20 is an existing lash adjuster, and includes a bottomed cylindrical body 21 and a bottomed cylindrical plunger 22 inserted into the body 21 so as to be vertically reciprocally displaceable. Have. The plunger 22 has a valve hole 23 on a bottom wall portion and a top portion 24 on the outer periphery of the upper end portion of the peripheral wall portion. The top portion 24 has a convex curved shape protruding upward, specifically, a hemispherical convex shape, and is formed substantially in the same shape as the rod contact portion 88. The top portion 24 has an oil guide hole 25 that penetrates the upper end of the plunger 22 in the thickness direction (vertical direction) at the center in the radial direction. The oil guide hole 25 has a shape that expands upward.

  The plunger 22 has a low-pressure chamber 26 inside. The body 21 has a high-pressure chamber 27 on the opposite side to the low-pressure chamber 26 with the bottom wall portion of the plunger 22 in the lower part. Hydraulic oil is introduced and stored in the low-pressure chamber 26 from an oil passage hole 13 described later of the push rod 10 via an oil guide hole 25. The hydraulic oil stored in the low-pressure chamber 26 is filled into the high-pressure chamber 27 through the valve hole 23.

  The high-pressure chamber 27 contains a spherical valve body 28, a cage-shaped retainer 29, a first spring 30, and a second spring 31. The valve body 28 is housed in a retainer 29 and is arranged so that the valve hole 23 can be opened and closed. The first spring 30 is housed in the retainer 29 and urges the valve body 28 upward. The valve element 28 is urged by the first spring 30 to close the valve hole 23. The second spring 31 contacts the opening end of the retainer 29 and urges the retainer 29 upward. Thereby, the state where the retainer 29 is pressed against the bottom wall portion of the plunger 22 is maintained.

  The plunger 22 has a plunger oil hole 32 penetrating in a radial direction in a peripheral wall portion. The body 21 has a body oil hole 33 in the peripheral wall portion, which communicates with the plunger oil hole 32 and penetrates in the radial direction. The hydraulic oil can be discharged from the low pressure chamber 26 to the outside of the lash adjuster 20 via the plunger oil hole 32 and the body oil hole 33.

  As shown in FIG. 2, the tappet case 40 has a cup shape as a whole, and includes an outer peripheral surface portion 41 along the up-down direction constituting an outer circumferential surface, and a lower surface portion 42 along a radial direction constituting a lower surface. have. The tappet case 40 is inserted into a guide hole 77 provided in the cylinder block 78, and is slidable vertically (axially). The lower surface portion 42 of the tappet case 40 is a flat surface that comes into contact with a cam 76 installed below. The cam 76 is provided on a camshaft 71 parallel to the axis of the rocker shaft 90.

  The lower portion 58 of the tappet case 40 is formed to be thicker in the radial direction than the upper portion 59. The lower portion 58 has a circumferential surface portion 43 extending in the radial direction and connected to the upper portion 59 in a stepped manner inside the tappet case 40. The lower portion 58 has an assembling hole 44 having a circular cross section, which extends in the up-down direction and whose upper end is opened at the radial center of the peripheral surface portion 43. The lash adjuster 20 is inserted into the mounting hole 44 of the tappet case 40 from above in a fitted state.

  The upper portion 59 of the tappet case 40 has therein a receiving space 45 communicating with the mounting hole 44. The receiving space 45 is defined between the plunger 22, the peripheral surface 43, and the upper portion 59 when the lash adjuster 20 is inserted into the mounting hole 44, and is opened upward.

  The outer peripheral surface portion 41 of the tappet case 40 has upper and lower sliding contact areas 46 and 47 slidable on the inner peripheral surface of the guide hole 77 of the cylinder block 78 at intervals in the vertical direction. The upper sliding contact region 46 is provided at the upper end of the outer peripheral surface portion 41, and the lower sliding contact region 47 is provided halfway in the vertical direction of the outer peripheral surface portion 41. The outer peripheral surface 41 of the tappet case 40 has a recess 49 between the upper and lower sliding contact areas 46 and 47. The outer peripheral surface portion 41 of the tappet case 40 has a groove-like vertical oil passage 51 extending in the vertical direction in communication with the recess 49 in the lower sliding contact region 47.

  Further, the tappet case 40 has an oil discharge hole 52 in the upper portion 59, which penetrates the inside and outside, opens to the inner peripheral surface, communicates with the receiving space 45, and opens at the upper end of the inner surface of the recess 49. ing. The hydraulic oil stored in the receiving space 45 of the tappet case 40 is discharged outside through the oil discharge hole 52.

  The tappet case 40 has an upper contact area 53 and a lower contact area 54 on the inner peripheral surface of the mounting hole 44 in the lower part 58, and further, between the upper and lower contact areas 53, 54. , And has a concave portion 55 that is concave outward in the radial direction. The upper contact area 53 is disposed at the upper end of the assembly hole 44 along the up-down direction, and the lower contact area 54 is disposed along the up-down direction of the assembly hole 44 along the up-down direction. I have.

  As shown in FIG. 2, when the lash adjuster 20 is properly inserted into the assembling hole 44 of the tappet case 40, the lower surface of the body 21 abuts against the inner bottom surface of the assembling hole 44, and the upper end of the body 21 is in the peripheral portion It is arranged at the same height position as 43. At this time, the outer peripheral surface of the body 21 comes into contact with the contact areas 53 and 54 of the tappet case 40 along the circumferential direction in a surface contact state, and the body oil hole 33 communicates with the concave portion 55 and faces. When the contact area 53 is higher than the body oil hole 33 and abuts on the outer peripheral surface of the body 21 along the circumferential direction, the operating oil flowing into the concave portion 55 from the body oil hole 33 leaks to the receiving space 45 side. Is regulated, so that the hydraulic oil can be sufficiently stored in the low-pressure chamber 26.

  As shown in FIG. 4, the push rod 10 is a rod-shaped member that extends vertically from the upper end to the lower end as a whole, and includes the later-described expanding portions 16 and 17 and sliding portions 11 and 12. It has a vertically symmetric structure. The push rod 10 is loosely inserted into a rod insertion hole (not shown) provided in the cylinder head 94 so as to be reciprocally displaceable.

  The push rod 10 has an oil passage hole 13 penetrating in the vertical direction (axial direction, length direction) at the center in the radial direction. The upper end and the lower end of the push rod 10 are expanded portions 16 and 17 having a predetermined thickness and projecting radially outward. The radially outer corners of the expanding portions 16 and 17 are chamfered in a curved shape.

  As shown in FIG. 3, the push rod 10 has a concave curved surface that expands upward in a trumpet shape, specifically, a hemispherical concave surface, and a cross-sectional shape along the vertical direction. The sliding part 11 has an upward arc shape. The upper end of the oil passage hole 13 is opened at the center of the sliding portion 11 in the radial direction. The sliding portion 11 slidably contacts the rod contact portion 88 of the rocker arm 80 and supports the other end of the rocker arm 80.

  As shown in FIG. 2, the push rod 10 has a concave curved surface shape, which expands downward in a trumpet shape, specifically, a hemispherical concave curved shape, and extends along the vertical direction in the enlarged portion 17 at the lower end. The sliding section 12 has a downwardly arcuate cross section. The lower end of the oil passage hole 13 is open at the center of the sliding portion 12 in the radial direction. The sliding portion 12 slidably contacts the top 24 of the lash adjuster 20 and is supported by the lash adjuster 20.

  The upper and lower sliding portions 11 and 12 have the same shape as each other, and have a shape capable of sliding on the rod contact portion 88 and the top portion 24. The radius of curvature of the inner circumference of the sliding portions 11 and 12 is slightly larger than the radius of curvature of the outer circumference of the rod contact portion 88 and the top 24. The upper and lower expanding portions 16 and 17 also have the same shape.

  Here, when the cam 76 rotates, the tappet case 40 that comes into contact with the cam 76 reciprocates in the guide hole 77 in the up and down direction, and the push rod 10 reciprocates in the up and down direction via the lash adjuster 20. As the push rod 10 reciprocates, the rocker arm 80 swings in a seesaw shape about the rocker shaft 90, and one end and the other end of the rocker arm 80 move up and down. When the valve contact portion 87 moves up and down at one end of the rocker arm 80, the valve stem 93 reciprocates in the up and down direction while receiving the urging force of the valve spring 98, and the valve body 96 switches between the open state and the closed state. Is displaced.

  When the tappet case 40 is raised and the push rod 10 presses the plunger 22 downward, the valve body 28 closes the valve hole 23, the plunger 22 and the body 21 become rigid, and the lowering of the plunger 22 is restricted. When the tappet case 40 descends and the pressing force acting on the plunger 22 decreases, the second spring 31 pushes up the plunger 22, and at the same time, the valve body 28 descends against the urging force of the first spring 30 and the valve hole is lowered. 23 is opened, and the hydraulic oil stored in the low pressure chamber 26 moves to the high pressure chamber 27 through the valve hole 23. When the plunger 22 moves up and down in response to the movement of the cam 76, the lift force of the cam 76 is attenuated and transmitted to the rocker arm 80 via the push rod 10, and the valve clearance is automatically adjusted. .

  The above operation of the lash adjuster 20 is performed based on the hydraulic pressure of the working oil supplied to the low-pressure chamber 26. The hydraulic oil is sequentially supplied to the low-pressure chamber 26 through the shaft oil hole 91, the communication hole 89, the screw oil hole 79, the oil passage hole 13, and the oil guide hole 25, and further filled into the high-pressure chamber 27 through the valve hole 23. . The hydraulic oil lubricates between the rod abutting portion 88 and the sliding portion 11 when moving from the screw communication oil hole 79 to the oil passage hole 13, and moves when moving from the oil passage hole 13 to the oil passage hole 25. Then, the space between the sliding portion 12 and the top portion 24 is lubricated.

  Part of the hydraulic oil accumulates on the peripheral surface 43 of the tappet case 40 after lubricating between the sliding portion 12 and the top 24, and is stored in the receiving space 45 of the tappet case 40. In the receiving space 45 of the tappet case 40, hydraulic oil or the like that is transmitted along the outer peripheral surface of the push rod 10 is also stored. As shown in FIG. 2, the hydraulic oil is stored in the receiving space 45 of the tappet case 40 up to the height position of the lower end of the oil discharge hole 52.

  Hydraulic oil enters the recess 49 of the tappet case 40 from the receiving space 45 of the tappet case 40 through the oil discharge hole 52, further falls down the vertical oil passage 51 and wraps around the lower surface 42, and the tappet case 40 and the cam 76. Lubricate between.

  Now, the sliding portions 11 and 12 of the push rod 10 are in a form that can correspond to both the rod contact portion 88 and the top 24. For this reason, the push rod 10 is turned upside down from the state shown in FIG. 1, and the sliding part 11 is brought into contact with the top part 24 with the sliding part 11 down, and the push rod 10 is brought into contact with the rod contact part 88 with the sliding part 12 up. Can also be used. That is, the push rod 10 is assembled between the rocker arm 80 and the lash adjuster 20 without distinguishing between the upper and lower sides. Therefore, the worker does not need to worry about the vertical direction (posture) of the push rod 10 at the time of assembling, and can proceed quickly with the work. In particular, since the sliding portions 11 and 12 have the same shape, the operator does not need to be aware of the vertical direction of the push rod 10. Therefore, the operator can proceed with the work more quickly without any doubt about the direction of the push rod 10.

  Furthermore, since the convex screw rod contact portion 88 is provided on the adjusting screw 82 separate from the arm body 81, the degree of freedom of the form of the arm body 81 can be ensured, and the rocker arm 80 can be machined. It can be done easily.

<Other embodiments>
Hereinafter, other embodiments will be briefly described.
(1) The lash adjuster may be configured by adding a slight addition or change to an existing one.
(2) The rocker arm may not have the adjusting screw at the other end, and may have a configuration in which the arm main body integrally has a rod contact portion having a convex curved surface in contact with the sliding portion of the push rod.
(3) The sliding portions at the upper end and the lower end of the push rod may be of any shape as long as they can slide in contact with the rod contacting portion and the top portion, and may have different shapes.
(4) The push rod may have a structure without an oil passage hole.

DESCRIPTION OF SYMBOLS 10 ... Push rod 11, 12 ... Sliding part 13 ... Oil passage hole 20 ... Lash adjuster 24 ... Top part 40 ... Tappet case 76 ... Cam 80 ... Rocker arm 81 ... Arm body 82 ... Adjust screw 87 ... Valve contact part 88 ... Rod Abutment

Claims (3)

A lash adjuster having a convex curved top protruding upward,
A tappet case that assembles the lash adjuster from above and reciprocates according to the rotation of the cam;
Extending in a direction intersecting the vertical direction from one end to the other end, having a valve abutting portion with which the valve abuts on the one end, and a convex curved rod abutting portion projecting downward on the other end. A rocker arm having
A concave curved slide extending from the upper end on the rocker arm side to the lower end on the lash adjuster side, and slidable on the upper end and the lower end in contact with both the rod contact portion and the top portion. And a push rod having a moving part.   The tappet structure according to claim 1, wherein the sliding portions at the upper end and the lower end of the push rod have the same shape.   The rocker arm extends from the one end to the other end, and is attached to the arm body having the valve contact part by screwing to the other end of the arm body, and protrudes downward from the arm body. The tappet structure according to claim 1, further comprising: an adjusting screw having the rod contact portion at a lower end portion.

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