JP2004278377A - Hydraulic lash adjuster for internal combustion engine - Google Patents

Abstract

An object of the present invention is to provide a hydraulic lash adjuster capable of separating air in lubricating oil and discharging the air to the outside.
A hydraulic lash adjuster (10) includes a body (11) mounted in an engine block (21), and a plunger (12) movably installed by fitting an outer peripheral surface (12c) to an inner peripheral surface (11a) of the body (11). A low-pressure chamber 14 is formed in the body 11, and a high-pressure chamber 15 is formed by the body 11 and the plunger 12. An inlet hole 11b communicating with an oil supply passage 21b formed in the engine block 21 is formed in the body 11, and a plunger hole 12i communicating with the low-pressure chamber 14 is formed in the plunger 12, and formed on an inner peripheral surface 11a of the body 11. The enlarged diameter portion 11c and the facing portion 12h formed on the outer peripheral surface 12c of the plunger 12 form a throttle passage 20 that connects the inlet hole 11b and the plunger hole 12i.
[Selection diagram] FIG.

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hydraulic lash adjuster for an internal combustion engine that adjusts a valve clearance of the internal combustion engine.
[0002]
[Prior art]
As a prior art, there is a related art related to a hydraulic lash adjuster that adjusts a valve clearance of an internal combustion engine by introducing high-pressure lubricating oil from an oil pump of the internal combustion engine into a low-pressure chamber formed in a plunger (for example, Patent Document 1). reference).
[0003]
[Patent Document 1]
Japanese Patent No. 3288744 (FIG. 1)
[0004]
[Problems to be solved by the invention]
Normally, air is often dissolved in the lubricating oil supplied from the oil pump, and when the lubricating oil containing air enters the low-pressure chamber in the plunger, it is interposed between the low-pressure chamber and the high-pressure chamber. It is conceivable that when one of the one-way valves opens, it enters the high-pressure chamber. If the lubricating oil containing a large amount of air enters the high-pressure chamber, it may subsequently precipitate as a gas, which prevents the hydraulic pressure in the high-pressure chamber from rising, prevents the lash adjuster from becoming rigid, When the valve is opened, it may lead to a malfunction of the valve.
[0005]
The present invention has been completed based on the above-described circumstances, and has as its object to provide a hydraulic lash adjuster capable of separating air in lubricating oil and discharging the air to the outside.
[0006]
[Means for Solving the Problems]
As means for achieving the above-mentioned object, the invention according to claim 1 is characterized in that a cup-shaped body attached to an internal combustion engine and an outer peripheral surface of the body are fitted with an inner peripheral surface of the body. And a cylindrical plunger having a low-pressure chamber formed therein, a high-pressure chamber formed by the body, and a communication path communicating the low-pressure chamber and the high-pressure chamber formed therein. And a one-way valve for closing the communication passage when the hydraulic pressure of the high-pressure chamber is equal to or higher than the hydraulic pressure of the low-pressure chamber, and introducing the hydraulic pressure of the internal combustion engine to the low-pressure chamber to the body and the plunger. A hydraulic pressure lash adjuster for an internal combustion engine is provided, wherein a hydraulic pressure introducing means is formed, and the hydraulic pressure introducing means includes a throttle passage.
[0007]
Also, the invention according to claim 2 is characterized in that the hydraulic pressure introducing means includes an inlet hole formed in the body into which the hydraulic pressure of the internal combustion engine is introduced, and a plunger hole formed in the plunger and communicating with the low-pressure chamber. 2. The hydraulic pressure for an internal combustion engine according to claim 1, wherein the throttle passage is formed by an inner peripheral surface of the body and an outer peripheral surface of the plunger, and communicates the inlet hole with the plunger hole. Rush adjuster.
[0008]
According to a third aspect of the present invention, the throttle passage is formed by causing an outer peripheral surface of the plunger to face an enlarged-diameter portion having an increased inner diameter of an inner peripheral surface of the body. Hydraulic lash adjuster for internal combustion engines.
[0009]
The invention according to claim 4 is characterized in that the throttle passage is formed by making the inner peripheral surface of the body face a reduced diameter portion having a reduced outer diameter of the outer peripheral surface of the plunger. The described hydraulic lash adjuster for an internal combustion engine was used.
[0010]
Function and effect of the present invention
<Invention of claim 1>
Since the hydraulic pressure introducing means formed in the body and the plunger includes the throttle passage, when the lubricating oil supplied from the internal combustion engine passes through the throttle passage and returns to a large space, the pressure of the lubricating oil is reduced. Air in the lubricating oil is separated by the reduced air contained as gas, which separates out the air from the lash adjuster. Can be prevented.
[0011]
<Invention of Claim 2>
Since a throttle passage is formed between the inlet hole and the plunger hole by the inner peripheral surface of the body and the outer peripheral surface of the plunger, it is not necessary to pierce the body or the plunger with a thin drill to form the throttle passage. In addition, the air in the lubricating oil can be separated and discharged to the outside of the lash adjuster, and the hydraulic lash adjuster can be easily manufactured. In addition, the size of the throttle passage can be freely set by the combination of the diameter of the inner peripheral surface of the body and the outer peripheral surface of the plunger, and the length of the throttle passage matches the length direction of the lash adjuster. The passage can be set.
[0012]
<Invention of Claim 3>
Since the throttle passage was formed by facing the outer peripheral surface of the plunger to the enlarged diameter portion with the inner diameter of the inner peripheral surface of the body increased, only the enlarged diameter portion was formed on the body side to form the throttle passage. There is no need to perform special processing, and a hydraulic lash adjuster that is easier to manufacture can be provided.
[0013]
<Invention of Claim 4>
The reduced diameter passage is formed by making the inner peripheral surface of the body face the reduced diameter portion where the outer diameter of the outer peripheral surface of the plunger is reduced. It is not necessary to apply special processing to the body by simply performing the above operation, and the hydraulic lash adjuster can be further easily manufactured.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
<First embodiment>
A first embodiment of the present invention will be described with reference to FIGS. In FIG. 1, a hydraulic lash adjuster 10 for an internal combustion engine, which is attached to a valve train of an engine that is an internal combustion engine, is inserted and fixed in a mounting hole 21 a of an engine block 21. The engine block 21 has an oil supply passage 21b through which high-pressure lubricating oil generated by an oil pump (not shown) is supplied. A valve stem 22a of the valve 22 is axially movably fitted in the stem hole 21c of the engine block 21, and a valve portion 22b attached to the tip of the valve stem 22a connects the intake passage 21d to the engine block 21 (not shown). It opens and closes in the cylinder. A spring retainer 23 is attached to the upper end of the valve stem 22a, and a valve return spring 24 is interposed between the spring retainer 23 and the upper surface of the engine block 21, and the valve 22 connects the intake passage 21d with the valve retainer spring 24. It is biased upward to close.
[0015]
The hydraulic lash adjuster 10 includes a cup-shaped body 11, and a substantially cylindrical plunger 12 fitted to an inner peripheral surface 11 a of the body 11 so as to be vertically movable. One end of the rocker arm 25 is engaged, and the other end of the rocker arm 25 is in contact with the upper surface of the spring retainer 23. An inlet hole 11b through which oil pressure is introduced from an oil supply passage 21b is formed at one location on the circumference of the side surface of the body 11, and a lubrication hole for supplying lubricating oil to the rocker arm 25 is formed at an upper end 12a of the plunger 12. 12b is formed. A cam 27 fixed to a cam shaft 26 is in contact with the upper part of the rocker arm 25, and the cam 27 has a protruding cam nose 27a.
[0016]
As shown in FIG. 2, after the hydraulic lash adjuster 10 is fitted to the inner peripheral surface 11 a of the body 11 so that the outer peripheral surface 12 c of the plunger 12 is engaged, the plunger retainer 13 is attached to the upper end of the body 11. It is installed. A bottom 12d is formed below the plunger 12, a low-pressure chamber 14 is formed above the bottom 12d, and a high-pressure chamber 15 is formed between the bottom 12d and the body 11. At the center of the bottom portion 12d, a communication passage 12e that connects the low pressure chamber 14 and the high pressure chamber 15 is formed.
[0017]
A retainer 17 is provided in the high-pressure chamber 15, and the retainer 17 is pressed against the bottom 12 d by the urging force of a retainer spring 16 abutting on the bottom of the high-pressure chamber 15. In order to close the communication passage 12e, a ball valve 18 is provided so as to engage with the valve seat 12f on the bottom 12d, and a valve spring 19 is interposed between the ball valve 18 and the retainer 17. The ball valve 18 is constantly urged upward by a valve spring 19, and is configured to open only when the hydraulic pressure in the low-pressure chamber 14 rises above the hydraulic pressure in the high-pressure chamber 15. The ball valve 18 corresponds to a one-way valve of the present invention.
[0018]
As shown in FIG. 3, on the surface of the body 11 facing the plunger 12, an enlarged diameter portion 11c whose inner diameter is larger than the inner peripheral surface 11a is formed over the entire circumference. On the other hand, a concave portion 12g is formed over the entire circumference of the surface of the plunger 12 facing the body 11, and an opposing portion 12h is formed substantially at the center of the concave portion 12g over the entire circumference. In the present embodiment, the outer diameter of the facing portion 12h is set to the same size as the outer diameter of the outer peripheral surface 12c. Further, a plunger hole 12i is formed at one location on the side surface of the plunger 12 so as to communicate the recess 12g and the low-pressure chamber 14. Between the enlarged diameter portion 11c of the body 11 and the opposing portion 12h of the plunger 12, there is formed a throttle passage 20, which is an annular narrow oil passage that limits the amount of lubricating oil passed. The inlet hole 11b, the enlarged diameter portion 11c, the concave portion 12g, the throttle passage 20, and the plunger hole 12i correspond to the hydraulic pressure introducing means of the present invention.
[0019]
Next, the operation of the hydraulic lash adjuster 10 will be described together with the operation of the valve train shown in FIG. High-pressure lubricating oil generated by an oil pump (not shown) and supplied to the oil supply passage 21b of the engine block 21 is introduced into the inlet hole 11b of the hydraulic lash adjuster 10. On the other hand, the cam 27 rotates together with the camshaft 26 to which the power of the engine is transmitted, and the cam nose 27a presses the rocker arm 25 from above.
[0020]
At this time, since the plunger 12 of the hydraulic lash adjuster 10 is pressed from above by one end of the rocker arm 25, the plunger 12 moves downward with respect to the body 11, and the lubricating oil in the high-pressure chamber 15 is compressed and the pressure increases. Rises. As the pressure in the high-pressure chamber 15 increases, some lubricating oil in the high-pressure chamber 15 passes between the inner peripheral surface 11a of the body 11 and the outer peripheral surface 12c of the plunger 12, and passes through the plunger hole 12i. 14, the overall length of the hydraulic lash adjuster 10 is slightly reduced. When the pressure in the high-pressure chamber 15 increases, the body 11 and the plunger 12 become integrally rigidized, and the hydraulic lash adjuster 10 functions as a fulcrum for the operation of the rocker arm 25. The other end of the rocker arm 25 presses down the valve portion 22b via the valve stem 22a connected to the spring retainer 23 while compressing the valve return spring 24, thereby opening the intake passage 21d with respect to the cylinder.
[0021]
Here, the high-pressure lubricating oil introduced into the inlet hole 11b of the hydraulic lash adjuster 10 passes through a throttle passage 20 formed between the enlarged diameter portion 11c of the body 11 and the facing portion 12h of the plunger 12. When the hydraulic pressure passes through the throttle passage 20 and returns to a wide space (a space formed by the enlarged diameter portion 11c and the concave portion 12g in this embodiment), the pressure of the lubricating oil is reduced and the air contained therein is reduced. Is deposited as a gas, whereby the air contained therein is separated from the lubricating oil. After separation, the air that is easily discharged rises and is discharged to the outside of the hydraulic lash adjuster 10 through the space between the inner peripheral surface 11a of the body 11 and the outer peripheral surface 12c of the plunger 12, and the lubricating oil is discharged from the plunger hole 12i at a low pressure. It is sent into the chamber 14 and is discharged outside through the lubrication hole 12b of the plunger 12, and functions as lubricating oil for the engagement surface between the rocker arm 25 and the plunger 12. Even if the air separated from the lubricating oil when passing through the throttle passage 20 enters the low-pressure chamber 14, the air is separated from the lubricating oil and has a small mass, so that the air flows out of the lubrication hole 12 b and out of the hydraulic lash adjuster 10. It is not discharged and enters the high-pressure chamber 15.
[0022]
When the cam nose 27a is turned upward from the lowest point with the rotation of the cam 27, the downward pressure of the rocker arm 25 is eliminated, and the plunger 12 is returned upward by the pressure in the high pressure chamber 15 and the urging force of the retainer spring 16. It is. When the pressure in the high-pressure chamber 15 decreases with the upward movement of the plunger 12 and becomes lower than the pressure in the low-pressure chamber 14, the ball valve 18 opens against the urging force of the valve spring 19, and the low-pressure chamber is opened. The lubricating oil in 14 flows into the high-pressure chamber 15 through the communication passage 12e, and the hydraulic lash adjuster 10 is extended. By extending the hydraulic lash adjuster 10, the gap between the upper end 12a of the plunger 12 and the rocker arm 25 can be filled.
[0023]
According to the above-described first embodiment, when the lubricating oil supplied from the internal combustion engine passes through the throttle passage 20 and returns to a wide space again, the pressure of the lubricating oil is reduced and the contained air is gaseous. By separating as follows, the air in the lubricating oil is separated, so that it is possible to discharge the air out of the lash adjuster 10 and prevent the air from entering the high-pressure chamber 15. Further, since the throttle passage 20 is constituted by the enlarged diameter portion 11c of the body 11 and the facing portion 12h of the plunger 12 opposed thereto, a narrow drill or the like is formed on the body 11 or the plunger 12 to form the throttle passage. There is no need to perform perforation, and manufacturing becomes easy. Further, the size of the throttle passage 20 can be freely set by a combination of the diameter of the enlarged diameter portion 11c of the body 11 and the facing portion 12h of the plunger 12, and the length of the throttle passage 20 is also set in the length direction of the lash adjuster 10. Therefore, the setting of the long throttle passage 20 is also possible.
[0024]
<Second embodiment>
Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, the inner peripheral surface 11a of the body 11 is not provided with an enlarged diameter portion, and instead, the plunger 12 is formed with a reduced diameter portion 12j whose outer diameter is smaller than that of the outer peripheral surface 12c. Is formed between the inner peripheral surface 11a of the body 11 and the reduced diameter portion 12j of the plunger 12. The other parts are the same as in the first embodiment, and a description thereof will be omitted.
[0025]
According to the second embodiment, the throttle passage 30 is formed by providing the reduced diameter portion 12j on the outer peripheral surface 12c of the plunger 12 that is easy to process without providing the enlarged diameter portion on the inner peripheral surface 11a of the body 11. Therefore, the hydraulic lash adjuster 10 that can be easily manufactured can be obtained.
[0026]
<Third embodiment>
Further, as a third embodiment, a concave portion 11d may be further formed on the inner peripheral surface 11a of the body 11 as shown in FIG.
[0027]
<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and the drawings. For example, the following embodiments are also included in the technical scope of the present invention, and furthermore, other than these, the scope which does not depart from the gist is described. Various changes can be made within the embodiment.
(1) The throttle passage does not necessarily have to be formed in an annular shape between the body and the plunger. For example, one or a plurality of slits are provided on the inner peripheral surface of the body or the outer peripheral surface of the plunger. The throttle passage may be formed by facing the outer peripheral surface of the plunger or the inner peripheral surface of the body.
(2) A cylindrical separator may be installed in the low-pressure chamber, and the air separated from the lubricating oil may be discharged from the outer periphery of the separator in the low-pressure chamber to the outside of the lash adjuster.
(3) The use of the hydraulic lash adjuster according to the present invention is not particularly limited, and is applicable to any internal combustion engine such as a gasoline engine and a diesel engine.
[Brief description of the drawings]
FIG. 1 is a view showing a valve train equipped with a hydraulic lash adjuster according to the present invention.
FIG. 2 is a cross-sectional view of the hydraulic lash adjuster according to the first embodiment.
FIG. 3 is an enlarged view of a main part of FIG. 2;
FIG. 4 is an enlarged view of a main part of a hydraulic lash adjuster according to a second embodiment.
FIG. 5 is an enlarged view of a main part of a hydraulic lash adjuster according to a third embodiment.
[Explanation of symbols]
10 hydraulic lash adjuster 11 body 11a body inner surface 11b inlet hole 11c enlarged diameter portion 12 plunger 12c plunger outer peripheral surface 12e communication passage 12h opposed portion 12i plunger hole 12j reduced diameter portion 14 Low pressure chamber 15 High pressure chamber 18 Ball valve 20 Throttle passage 30 Throttle passage

Claims (4)

A cup-shaped body mounted in the internal combustion engine,
The outer peripheral surface is movably installed in the body by fitting the inner peripheral surface of the body, and a low-pressure chamber is formed therein, and a high-pressure chamber is formed by the body and the low-pressure chamber. A cylindrical plunger formed with a communication passage communicating the chamber and the high-pressure chamber;
When the hydraulic pressure of the high-pressure chamber is equal to or higher than the hydraulic pressure of the low-pressure chamber, a one-way valve that closes the communication path,
A hydraulic lash adjuster for an internal combustion engine, wherein the body and the plunger are formed with hydraulic pressure introducing means for introducing a hydraulic pressure of an internal combustion engine into the low pressure chamber, and the hydraulic pressure introducing means includes a throttle passage. . The hydraulic pressure introducing means includes an inlet hole formed in the body through which a hydraulic pressure of the internal combustion engine is introduced, and a plunger hole formed in the plunger and communicating with the low-pressure chamber. 2. The hydraulic lash adjuster for an internal combustion engine according to claim 1, wherein the hydraulic lash adjuster is formed by an inner peripheral surface and an outer peripheral surface of the plunger, and communicates the inlet hole with the plunger hole. 3. 3. The hydraulic lash adjuster for an internal combustion engine according to claim 2, wherein the throttle passage is formed by causing an outer peripheral surface of the plunger to face an enlarged-diameter portion having an increased inner diameter of an inner peripheral surface of the body. 3. The hydraulic lash adjuster for an internal combustion engine according to claim 2, wherein the throttle passage is formed by making an inner peripheral surface of the body face a reduced diameter portion having a reduced outer diameter of an outer peripheral surface of the plunger.

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