JP2019060313A - Lash adjuster - Google Patents

Abstract

To prevent an oil from being discharged from a plunger by stopping an engine in a state where an oil introduction hole of the plunger is turned downwards, in a lash adjuster that is used for a slant type internal combustion engine.SOLUTION: A peripheral wall of a plunger 13 is formed asymmetrical in such a manner that the peripheral wall at the side of a second communication hole 25 becomes thinner and at the opposite side thereof becomes thicker, thereby displacing a centroid 27 of the plunger 13 to an opposite side of an oil introduction hole 25 with a shaft center (a shaft center of an outer periphery) 26 being held therebetween. When a lash adjuster 11 is integrated into a cylinder head 1, the plunger 13 is automatically rotated in such a manner that the centroid 27 comes to a lower side. Therefore, after an engine is stopped, an oil is kept stored in a state where a liquid level 28 is kept at a height of the oil introduction hole 25. As a result, in the case of next start, lubrication can be performed simultaneously with cranking and noise can be prevented from being generated or wear-out can be prevented from progressing.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a hydraulic lash adjuster provided in a cylinder head of an internal combustion engine and functioning as a rocking fulcrum of a rocker arm that operates an intake valve or an exhaust valve.

  The hydraulic lash adjuster includes a bottomed cylindrical body mounted in a mounting hole provided in a cylinder head, and a hollow plunger rotatably and slidably inserted in the body. The plunger is biased in the forward direction by a check valve consisting of a ball and a spring.

  Further, an annular groove is formed in the plunger, and an oil introduction hole communicating with the outer periphery and the inner periphery is formed in one of the annular grooves in the circumferential direction, and the oil from the tip of the plunger is rocker arm The lubrication is performed by discharging toward the piston, and when the pressure of the rocker arm against the plunger becomes excessively high, the oil pushes the ball and escapes from the bottom to keep the pressure of the oil inside the plunger constant and the rocker arm The support reaction force is kept constant.

  And, for example, in a slant type internal combustion engine in which the cylinder bore axis is largely inclined to the horizontal side, the lash adjuster may be largely inclined to the horizontal side or may become substantially horizontal. In this case, the plunger is a body When the oil introduction hole opens downward, the oil is pulled out of the inside of the plunger when the engine is stopped, and the rocker arm is not lubricated at the next start. It will be supported, which may cause noise during start-up, and may lead to premature wear of the rocker arm and the plunger.

  In this respect, Patent Document 1 sets the plunger and the oil introduction hole to be held in an upward facing posture by holding the body and the plunger non-rotatably by the pin engaged with the cylinder head. It is disclosed that oil remains in the inside of the plunger even after engine stop.

JP, 2014-43803, A

  In Patent Document 1, the position of the plunger can be maintained so that the oil introduction hole is upward, so oil can be retained in the plunger, but special processing must be performed on the body and the cylinder head. Therefore, not only the cost is increased, but also the pin must be fitted while checking the posture of the plunger and the body, so that the assembly of the lash adjuster becomes very troublesome.

  The present invention has been made to improve such a current situation.

According to the lash adjuster of the present invention, according to claim 1,
A bottomed cylindrical body mounted in a mounting hole provided in a cylinder head, and a hollow plunger rotatably and slidably inserted in the body, the plunger having an outer periphery thereof An oil introduction hole communicating with the inner circumference and the inner circumference,
The plunger is formed with an eccentric means for shifting the center of gravity at a portion opposite to the oil introduction hole with respect to the axial center.

  The present invention can be developed in various ways. For example, in claim 2 of the present invention, a portion of the plunger opposite to the oil introducing hole with respect to the axial center is formed thicker than a portion provided with the oil introducing hole. doing.

  In the present invention, when applied to a slant type internal combustion engine or the like, when the lash adjuster is in the inclined posture or the horizontal posture, the plunger is automatically rotated by gravity so that the eccentric side is down and the eccentric side is When it goes down, it is held stably in that posture. Therefore, even if the body is rotatably fitted in the mounting hole of the cylinder head at the stage of assembly to the cylinder head or the plunger is fitted in the body in a rotatable state, the posture of the plunger is It can be automatically corrected so that the introduction hole is upward.

  Therefore, when assembling the lash adjuster, it is not necessary to check the posture one by one, and it is possible to prevent an increase in the time of the assembling operation. In addition, since it is not necessary to perform special processing on the body or the cylinder head, it is possible to suppress an increase in processing cost.

  As an eccentric means, for example, it is possible to embed or fix a weight made of a metal having a large specific gravity in a portion opposite to the oil introduction hole, but as in claim 2, the wall thickness is formed asymmetrically. Since the eccentric means can be made eccentric without requiring a special additional member, the time for member management and the time for assembly can be eliminated. In addition, since the members do not come off due to vibration, the reliability is also excellent.

1 is a partial longitudinal front view of an internal combustion engine. (A) is a longitudinal front view of the intake side lash adjuster, (B) is a longitudinal front view of the exhaust side lash adjuster. (A) is a cross-sectional view taken along the line III-III in FIG. 2, (B) is another example similar to (A), and (C) is a vertical cross-sectional front view of another embodiment.

(1). Basic Structure Next, an embodiment of the present invention will be described based on the drawings. The present embodiment is applied to an internal combustion engine for automobiles. FIG. 1 is a front elevational view of a portion of a head portion of an internal combustion engine as viewed from the direction of the crankshaft axis, and the internal combustion engine is a slant type in which a cylinder bore axis O is made close to horizontal H (cylinder bore The axis O is inclined to form an angle of less than 30 degrees with respect to the horizontal H).

  Although the internal combustion engine has a cylinder head 1, the cylinder head 1 of this embodiment has a laminated structure of an upper portion 2 and a lower portion 3, and a bearing portion provided on the upper portion 2 is an intake valve camshaft 4 and the exhaust valve camshaft 5 are rotatably held via a cam cap (not shown). Naturally, on the camshafts 4 and 5, cams 6 and 7 for opening and closing valves are formed in pairs corresponding to the respective cylinders. The upper part 2 of the cylinder head 1 is displayed roughly.

  In the cylinder head 1, rocker arms 8 are disposed at a pair corresponding to the cams 6 and 7. The rocker arm 8 is a free type without a pivot, one end located inside the cylinder head 1 is in contact with the valve stem 9 from above through the shim 10, and the other end is a hydraulic lash It is supported by the adjuster 11. It is needless to say that the valve shaft 9 is biased in the valve closing direction via the spring 12.

  The lash adjuster 11 has a basic structure similar to that of the prior art, and includes a plunger 13 for supporting the rocker arm 8 and a bottomed cylindrical body 14 in which the plunger 13 is slidably and rotatably fitted. The body 14 is fitted into a mounting hole 1a formed in the cylinder head 1 (3).

  A space between the bottom of the plunger 13 and the bottom of the body 14 is a high pressure chamber 15. In the high pressure chamber 15, a check valve having a support spring 16 and a check ball 17 is disposed. The check ball 17 is supported by an auxiliary spring 18 held in a bowl-like case, and closes the pressure adjustment hole 19 from the outside. A lubricating hole (discharge hole) 20 is opened at the tip of the plunger 13 that abuts on the rocker arm 8.

  A first annular recess 21 is formed in a portion of the outer peripheral surface of the body 14 that is close to the rocker arm 8, and one first communication hole 22 is formed at an end of the first annular recess 21 that is closer to the bottom. Vacant. The first annular recess 21 communicates with an oil passage 23 formed in the lower portion 3 of the cylinder head 1. The oil passage 23 extends in the axial direction of the cam shafts 4 and 5.

  On the other hand, on the outer peripheral surface of the plunger 13, a second annular recess 24 communicating with the first communication hole 22 in the entire range of the sliding stroke is formed, and at the location of the second annular recess 24 The second communication hole 25 penetrating the inside and the outside of the plunger 13 is open as the oil introduction hole described in the above. Accordingly, the oil flows from the oil passage 23 into the inside of the plunger 13 via the first annular recess 21, the first communication hole 22, the second annular recess 24 and the second communication hole 25.

  Since the plunger 13 is biased by the support spring 16, the rocker arm 8 is biased by the plunger 13, and the contact surface between the plunger 13 and the rocker arm 8 is lubricated with oil. Further, when the rocker arm 8 swings, the support spring 16 expands and contracts, whereby the plunger 13 slides and the support force of the rocker arm 8 is held constant. Also, the oil pressure acts to push the rocker arm 8. Accordingly, the rocker arm 8 is supported by the elastic restoring force of the support spring 16 and the pressure of the oil.

  When the pressing force of the rocker arm 8 against the plunger 13 becomes excessive, the flow of oil from the lubrication hole 20 stops, and the pressure of the oil inside the plunger 13 increases and the oil inside the plunger 13 checks the check ball 17 The pressure is released to the high pressure chamber 15. As a result, the pressing action of the rocker arm 8 by the oil is reduced and the plunger 13 is retracted against the support spring 16 so that the support force on the rocker arm 8 is automatically adjusted to be constant.

(2) Eccentricity means The peripheral wall of the plunger 13 is thick so that the second communication hole 25 is thin and the thick wall 13a is opposite to the second communication hole 25 with respect to the axial center 26 of the outer periphery. Are uneven, whereby the center of gravity 27 is shifted to the opposite side of the second communication hole 25 with the axis 26 in between. That is, by forming the wall thickness of the plunger 13 asymmetrically on both sides of the shaft center 26, the eccentric means described in the claims is realized.

  In FIG. 3A, by setting the center of the inner periphery of the plunger 13 above the axial center 26 of the outer periphery, the thickness is set to be thicker as the distance from the second communication hole 25 increases. However, as shown in (B), the thick portion (or inward protrusion) 13a may be formed only on the opposite side across the second communication hole 25.

  The lash adjuster 11 is one unit in a state in which the plunger 13 is incorporated into the body 14, and the relative posture between the plunger 13 and the body 14 is not united in the shipped state, and the first communication hole 22 The positional relationship between the second communication hole 25 and the second communication hole 25 varies.

  However, when the lash adjuster 11 is incorporated into the cylinder head 1, the position of the first communication hole 22 in the body 14 is not uniform, but after being incorporated, the plunger 13 has its center of gravity 27 below by gravity. , And once its center of gravity 27 is down, its posture is maintained.

  Therefore, even if the engine is stopped, the oil remains accumulated in the plunger 13 with the oil surface 28 held at the height position of the second communication hole 25. The accumulation amount of oil increases as the inclination angle of the lash adjuster 11 with respect to the vertical line increases (as the inclination angle with respect to the horizontal decreases). In the horizontal posture, the inside of the plunger 13 becomes full when the leakage from the lubrication hole 20 is ignored. It will be in a state (If there is a leak from the lubrication hole 20, it can be said that it will accumulate most in the inclined posture as shown in FIG. 2 (B)).

  Therefore, at the time of the next start, lubrication between the rocker arm 8 and the plunger 13 is performed simultaneously with cranking, and as a result, it is possible to prevent the progress of the abrasion caused by the noise. In the embodiment, the thick portion 13a is formed over the entire length of the plunger 13. However, the thick portion 13a can be formed at an arbitrary position such as half of the bottom portion.

  In the embodiment, the automatically adjustable lash adjuster 11 is disposed on the intake side and the exhaust side. However, for example, the rocker arm 8 for the exhaust valve can be supported by a fixed support device. . In this case, while the lash adjuster 11 is used, the support spring 16 can be replaced with a spacer to form a fixed support device without arranging the support spring 16. In this case, the clearance adjustment between the rocker arm 8 and the valve stem 9 may be performed by the shim 10.

(3). Other Embodiments In the second embodiment shown in FIG. 3C, as the eccentric means, a large number of light stealing holes 29 are formed on the side of the plunger 13 where the second communication hole 25 exists. . Although the meat theft hole 29 penetrates in and out in the figure, it may be formed in a non-penetrating shape opened only at the outer periphery. Moreover, it is also possible to form in slit shape long to an axial direction or circumferential direction. In any case, the meat theft hole 29 needs to be formed within a range that does not impair the strength of the plunger 13.

  The structure of the second embodiment can be replaced with or used in combination with the first embodiment. In combination, the movement of the center of gravity is larger, so that the automatic rotation of the plunger 13 can be ensured.

  The reason why the second annular recess 24 is formed in the plunger 13 is to allow the oil to flow in from the first communication hole 22 regardless of the position of the second communication hole 25 of the plunger 13. However, in the present invention The second annular recess 24 is not necessarily required because the posture of the plunger 13 is automatically changed so that the second communication hole 25 faces upward. Therefore, as shown as a third embodiment in FIG. 3C, the second communication hole 25 may be formed in an axially long long groove 30 formed on the outer periphery of the plunger 13.

  In the structure of the third embodiment, since the strength of the plunger 13 is higher than that in the case where the second annular recess 24 is formed, the location of the second communication hole 25 may be thinned, as shown in FIG. It becomes easy to form the meat theft hole 29 on the side of the second communication hole 25 and the shift amount of the center of gravity 27 can be further increased.

  The present invention can be embodied in various other ways. For example, as an eccentric means, it is also possible to embed a metal having a large specific gravity in a portion of the outer periphery of the plunger opposite to the second communication hole with respect to the axial center.

  The present invention can be embodied in a lash adjuster of an internal combustion engine. Therefore, it can be used industrially.

Reference Signs List 1 cylinder head 4, 5 cam shaft 6, 7 cam 9 rocker arm 9 valve shaft 11 lash adjuster 12 spring 13 plunger 13a thick part constituting eccentric means 14 body 21 first annular recess 22 first communicating hole 24 second annular Recess 25 second communication hole (oil introduction hole)
26 Axis (axis of outer circumference)
27 Center of gravity 28 Oil level

Claims (2)

It has a bottomed cylindrical body mounted on a cylinder head, and a hollow plunger rotatably and slidably inserted in the body, the plunger having an outer periphery and an inner periphery thereof. It is the structure in which the communicated oil introduction hole is formed,
The plunger has an eccentric means for shifting the center of gravity at a portion opposite to the oil introduction hole with respect to the axial center,
Lash adjuster. The portion of the plunger opposite to the oil introducing hole with respect to the axial center is formed thicker than the portion provided with the oil introducing hole, thereby forming the eccentric means.
A lash adjuster according to claim 1.

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