JPH057443Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to an improvement in a valve operating system for an internal combustion engine, particularly an end-pivot type valve operating system in which one end of a swing arm is supported by a hydraulic lifter.

BACKGROUND ART FIG. 3 shows a configuration example of a conventional end-pivot type valve operating system (see Japanese Patent Application Laid-Open No. 60-209609). In the figure, 31 is an intake and exhaust valve equipped with a valve spring 32, 33 is a valve drive cam, and 34 is a swing arm that transmits the lift of this valve drive cam 33 to the intake and exhaust valve 31. One end is swingably supported by a hydraulic lifter 36 installed in the cylinder head 35, and the other end contacts the stem end of the intake and exhaust valve 31,
In addition, a cam follower portion 34a on the rear surface of the substantially central portion is in sliding contact with the valve drive cam 33.

The hydraulic lifter 36 has a bottomed cylindrical body 37 and a plunger 38 that is slidably fitted into the body 37 and has a hemispherical pivot portion 38a at its upper end. A hydraulic chamber 39 is defined in the lower part of the body 37 by the plunger 38, and a check valve 41 is provided between the oil reservoir chamber 40 in the plunger 38 and the hydraulic chamber 39.
is installed. A coil spring 42 is disposed within the hydraulic chamber 39 and biases the plunger 38 in the projecting direction. And the oil sump chamber 4
0 is always in communication with a lubricating oil passage 45 of the cylinder head 35 via a communication hole 43 on the side of the plunger 38 and a communication hole 44 on the side of the body 37.

That is, when the base circle of the valve drive cam 33 is in contact with the swing arm 34, the plunger 3 is moved by the action of the coil spring 42.
8 protrudes, keeping the valve clearance at zero and introducing lubricating oil into the hydraulic chamber 39. Also, when the cam is lifted, the check valve 41
Since the lubricating oil is sealed inside, the intake and exhaust valves 31 can be kept open against the reaction force of the valve spring 32. At this time, some lubricating oil leaks from the fitting between the body 37 and the plunger 38, but when the cam lift ends, the plunger 38 immediately protrudes and the lubricating oil is replenished into the hydraulic chamber 39, and by repeating this process, the lubricating oil is refilled. Valve clearance is always automatically adjusted to zero.
Incidentally, an air vent hole 46 is provided in the plunger 38 so that air mixed into the lubricating oil is discharged from the upper part of the oil reservoir chamber 40.

Problems to be Solved by the Invention In the conventional valve operating system as described above, lubricating oil leaking from the hydraulic lifter 36 flows over the upper surface of the cylinder head 35 and is collected without particularly lubricating other parts. Lubrication between the valve drive cam 33 and the cam follower portion 34a of the swing arm 34 is carried out separately from the hydraulic lifter 36, specifically through a lubricating oil passage formed through the valve drive cam 33 and a cam bracket (not shown). This is done by spraying lubricating oil from a lubricating oil passage provided in the Therefore, the spraying distance is relatively long and there is a drawback that a good oil film cannot be formed. In addition, as a result of opening a large number of lubricating oil passages in addition to the hydraulic lifter 36, when the oil pressure is low and the amount of oil supplied is low, such as during idling, sufficient oil pressure is supplied to the hydraulic lifter 36.
There is also a possibility that the amount of oil cannot be supplied.

In addition, in Japanese Patent Application Laid-open No. 61-34304, a communication hole that also serves as an air vent hole is formed in the pivot part, and lubricating oil is guided between the pivot part and the recessed part of the swing arm. A configuration in which an oil passage is provided from the bottom to the sliding contact part with the valve drive cam is disclosed, but in this structure, the communication hole is opened and closed by the sliding movement of the swing arm, and the lubricating oil is supplied only when the cam lifts. Spraying is becoming more and more common. Therefore, at low engine speeds when lubrication of the cam is most necessary, lubrication is insufficient, leading to an increase in friction loss torque. Furthermore, air discharge from the hydraulic lifter's oil sump chamber is stopped at the cam base circle, so at engine high speeds where 30 to 50% air is mixed in, causing cloudy lubricating oil, the air in the oil sump chamber is Separation and discharge of air become insufficient, which tends to cause air to enter the hydraulic chamber and cause malfunction of the hydraulic lifter.

In addition, a structure in which a cam follower roller is rotatably provided on the swing arm as a cam follower for the valve drive cam is shown in U.S. Pat. In this case, the bearing of the cam follower roller was lubricated by droplets of lubricating oil dripping from the valve drive cam, and the lubrication was extremely unstable.

Means for solving the problems In order to solve the above problems, this invention
One end of the swing arm is swingably supported by a plunger of a hydraulic lifter installed in the cylinder head, and the other end abuts the stem end of the intake and exhaust valve. In a valve operating system for an internal combustion engine that is in contact with a valve drive cam, a space whose periphery is sealed is formed between a fitting recess provided at one end of the swing arm and a pivot section at the tip of the plunger. At the same time, a communication hole is formed in the pivot portion to provide constant communication between the oil reservoir chamber in the hydraulic lifter and the valve drive cam, and a communication hole is formed in the pivot portion to provide constant communication between the oil reservoir chamber in the hydraulic lifter and the valve drive cam. The feature is that oil passages are formed toward each contact surface.

Function A part of the lubricating oil that is pumped from the lubricating oil passage in the cylinder head to the hydraulic lifter constantly flows from the oil reservoir chamber to the above-mentioned space, and from there, it passes through the oil passage and comes into contact with the roller shaft and valve drive cam. supplied to the surface.

Embodiment FIGS. 1 and 2 show an embodiment of a valve train according to this invention. In this embodiment, a pair of intake and exhaust valves 1 are configured to be opened and closed simultaneously via a single swing arm 2.
numeral 4 indicates a valve spring, numeral 4 indicates a valve drive cam, and numeral 5 indicates a hydraulic lifter.

The hydraulic lifter 5 has basically the same structure as the conventional one, and includes a body 8 having a bottomed cylindrical shape that fits into the cylinder head 7, and a body 8 that is slidably inserted into the body 8. and a plunger 9,
A hemispherical pivot portion 9a is formed at the upper end of the plunger 9. Further, a hydraulic chamber 10 is defined in the lower part of the body 8 by the plunger 9, and a check valve 12 is disposed between the oil reservoir chamber 11 in the plunger 9 and the hydraulic chamber 10, and A coil spring 13 is disposed within the hydraulic chamber 10 to bias the plunger 9 in the projecting direction. The oil reservoir chamber 11 includes a communication hole 14 on the side surface of the plunger 9 and a communication hole 1 on the side surface of the body 8.
The lubricating oil passage 16 of the cylinder head 7 is always in communication with the lubricating oil passage 16 of the cylinder head 7 via the lubricating oil passage 16, and a communication hole 17 that communicates with the oil reservoir chamber 11 is formed through the central portion of the pivot portion 9a.

In addition, the swing arm 2 has a fitting recess 18 formed at one end that fits into the pivot portion 9a of the plunger 9 and is slidably supported, and the other end of the swing arm 2 is bifurcated and has an intake and exhaust valve, respectively. A cam follower roller 19 that abuts the stem end 1a of the valve drive cam 1 and substantially the center thereof is rotatably mounted via a roller shaft 20. The cam follower roller 19 abuts the valve drive cam 4.
Here, the fitting recess 18 is formed in a spindle shape as shown in FIG. It is formed. An oil passage 22 is formed in the swing arm 2 from 21 to the contact surface between the valve drive cam 4 and the cam follower roller 19, and an oil passage 23 is formed towards the roller shaft 20. has been done. The oil passage 23 further communicates with an oil passage 24 formed in the axial direction of the roller shaft 20, as shown in FIG. Lubricating oil is introduced to the surface.

In the above configuration, lubricating oil for the engine is supplied from the lubricating oil passage 16 to the oil reservoir chamber 11 of the hydraulic lifter 5, from which part of the oil is introduced into the hydraulic chamber 10, and the remaining part passes through the communication hole 17 to the oil reservoir chamber 11 of the hydraulic lifter 5. It constantly flows into oil passages 21 and is further forced into oil passages 22 and 23.
The oil is sprayed onto the contact surface between the valve drive cam 4 and the cam follower roller 19 via the oil passage 22, and is directly supplied between the roller shaft 20 and the cam follower roller 19 via the oil passage 23. These lubricating oil supplies are always performed regardless of the cam lift state.

Therefore, the lubricating oil can be sprayed from a relatively close position to the contact surface between the valve drive cam 4 and the cam follower roller 19, and regardless of whether the valve drive cam 4 is lifted or not, the lubricant can be sprayed toward the contact surface. Once upon a time, it was possible to supply lubricating oil accurately. In other words,
The contact surface between the valve drive cam 4 and the cam follower roller 19 is constantly lubricated, and friction loss is reduced, especially at low rotations. Furthermore, the roller shaft 20 can be lubricated much more reliably than when spraying from the outside! As described above, the lubricating oil overflowing from the oil reservoir chamber 11 of the hydraulic lifter 5 is used to lubricate the cam follower roller 19, so even when the oil pressure is low and the amount of oil supplied is low, such as during idling, Sufficient oil pressure and amount of oil can be supplied to the hydraulic lifter 5 to ensure normal operation. Furthermore, the communication hole 17 also serves as an air bleed hole for discharging air from the hydraulic lifter 5, but according to the above configuration,
Since lubricating oil is constantly spouted out through the oil passage 22, and the tip of the oil passage 22 is always open to the atmosphere, even in the high-speed range of the engine where a large amount of air is mixed into the lubricating oil, it can be separated in the oil sump chamber 11. The air is quickly discharged to the outside, and intrusion into the hydraulic chamber 10 is reliably prevented. Moreover, since air is also discharged together with the lubricating oil through the oil passage 23, the air can be discharged even more smoothly.

Effects of the invention As is clear from the above explanation, the valve train for an internal combustion engine according to the invention can satisfactorily lubricate the contact surface of the cam follower roller with the roller shaft and valve drive cam, and It is possible to improve the durability of the fluorescent roller and reduce friction loss. Further, it is possible to prevent the oil pressure and oil amount of the hydraulic lifter from decreasing during idle time, etc., thereby ensuring normal operation. In addition, since the air is discharged quickly at all times without impairing the air discharge from the hydraulic lifter, it is possible to reliably prevent air from entering the hydraulic chamber and ensure normal operation of the hydraulic lifter.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of essential parts showing an embodiment of this invention, FIG. 2 is a top view of the same, and FIG. 3 is a cross-sectional view showing a conventional valve operating system. 1... Intake and exhaust valve, 2... Swing arm, 4...
... Valve drive cam, 5 ... Hydraulic lifter, 9 ... Plunger, 9a ... Pivot part, 11 ... Oil reservoir chamber, 18 ... Fitting recess, 19 ... Cam follower roller, 20 ... Roller shaft, 21 ……Material〓, 22,
23...Oil passage.

Claims (1)

[Scope of utility model registration request] One end of the swing arm is swingably supported by a plunger of a hydraulic lifter installed in the cylinder head, and the other end abuts the stem end of the intake and exhaust valve. In a valve operating system for an internal combustion engine that is in contact with a valve drive cam, a space whose periphery is sealed is formed between a fitting recess provided at one end of the swing arm and a pivot section at the tip of the plunger. At the same time, a communication hole is formed in the pivot portion to provide constant communication between the oil reservoir chamber in the hydraulic lifter and the valve drive cam, and a communication hole is formed in the pivot portion to provide constant communication between the oil reservoir chamber in the hydraulic lifter and the valve drive cam. A valve train for an internal combustion engine, characterized in that oil passages are formed toward contact surfaces.